English Learning Center

Glossary - Sociology (A-Z)

2008-03-23T05:56:00.000-07:00

Absolute poverty- a deprivation of resources that is life threatening

Civil religion- a quasi-religious loyalty binding individuals in a basically secular society

Class system- a system of social stratification based on individual achievement

Colonialism- the process by which some nations enrich themselves through political and economic control of other countries

Cultural lag- the fact that cultural elements change at different rates, which may disrupt a cultural system

Cultural relativism- the practice of judging a culture by its own standards

Culture- the beliefs, values, behavior, and material objects that define a people’s way of life

Culture shock- persona disorientation that accompanies exposure to an unfamiliar way of life

Davis-Moore thesis- the assertion that social stratification is a universal pattern because it has beneficial consequences for the operation of a society

Dramaturgical analysis- Erving Goffman’s term for the investigation of social interaction in terms of theatrical performance

Endogamy- marriage between people of the same social category

Ethnicity- a shared cultural heritage

Ethnocentrism- the practice of judging another culture by the standards of one’s own culture

Exogamy- marriage between people of different social categories

Gender- the significance a society attaches to biological categories of female and male

Generalized other- George Herbert Mead’s term for widespread cultural norms and values we use as references in evaluating ourselves

Global perspective- the study of the larger world and our society’s place in it

Groupthink- the tendency of group members to conform by adopting a narrow view of some issue

Homogamy- marriage between people with the same social characteristics

Humanizing bureaucracy- fostering an organizational atmosphere that recognized and encourages the contributions of everyone

Ingroup- a social group commanding a member’s esteem and loyalty whose identity is in part based on an “outgroup”, or opposition group

Liberation theology- a fusion of Christian principles with political activism, often Marxist in character

Looking-glass-self- Cooley’s assertion that the self is based on how others respond to us; seeing ourselves through the eyes of others and their reactions and feedback they give us about ourselves

Multiculturalism- an educational program recognizing past and present cultural diversity in U.S. society and promoting the equality of all cultural traditions

Multinational corporation- a large corporation that operates in many different countries

Neocolonialism-a new form of global power relationships that involves not direct political control but, rather through economic exploitation and political manipulation by multinational corporations often support by their governments

Nonverbal communication- communication using body movements, gestures, and facial expressions rather that speech

Norms- rules, guidelines and expectations by which a society guides the behavior of its members

Nuclear family- (conjugal family) a family unit composed of one or more parents and their children

Outgroup- a social group toward which one feels competition or opposition

Pluralism- a state in which racial and ethnic minorities are distinct but have social parity (equality)

Prejudice- an attitude involving a rigid and irrational generalization about an entire category of people, usually remarking on their inferiority

Race- a category composed of humans who share certain biologically transmitted traits that members of a society deem socially significant; in reality biology doesn’t recognize “races” because the differences genetically are too small and insignificant

Rationalization of society- Max Weber’s term for the historical change from tradition to more scientifically based rationality as the dominant mode of human thought

Rational-legal authority- (also bureaucratic authority) power legitimized by legally enacted rules and regulations

Religion- a social institution involving beliefs and practices based upon a conception of the sacred

Role- behavior expected of someone who holds a particular status

Role set- a number of roles attached to a single person

Sapir-Whorf hypothesis- a hypothesis stating that people perceive the world through the cultural lens of their unique language

Scapegoat- a person or category of people, typically with little power, whom people unfairly blame for their own troubles

Secularization- the historical decline in the importance of the supernatural and the sacred; a declining influence of religion in everyday life

Sexual harassment- comments, gesture, or physical contact of a sexual nature that is deliberate, repeated and unwelcome

Social-conflict paradigm- a framework for building theory based on the assumption that society is characterized by inequality and conflict that generate change

Socialization- the lifelong social experience by which individuals develop human potential and learn patters of their culture

Social stratification- a system by which society ranks categories of people in a hierarchy

Society- people who interact in a defined territory and share culture

Sociocultural evolution- the Lenskis’ term for the process of change that results from a society’s gaining new cultural information, particularly technology

State capitalism- an economic and political system in which companies are privately owned although they cooperate closely with the government

Status- a recognized social position and identity that an individual occupies

Stereotype- a set of overgeneralizations concerning some category of people, some positive stereotypes exists, but most are negative

Stigma- a powerfully negative social label that radically changes a person’s self-concept and social identity

Structural-functional paradigm- a framework for building theory based on the assumption that society is a complex system whose parts work together to promote stability

Subculture- cultural patterns that distinguish some segment of a society’s population; variations within a society regarding some aspects of religion, or language, or traditions/customs, or outward symbols/appearance that sets them apart from the mainstream or dominant culture

Sustainable ecosystem- the human use of the natural environment to meet the needs of the present generation without threatening the prospects of future generations

Symbolic-interaction paradigm-a theoretical framework based on the assumption that society is the product of the everyday interactions of individuals

Thomas theorem-W.I. Thomas’s assertion that situations we define as real become real in their consequences ("America is behind the spread of secularism, modernization and capitalism, so we must attack them with terrorism"; "Iraq has weapons of mass destruction and will use them against us, so we must attack them")

Urban renewal- government programs intended to revitalize cities

Values-culturally defined standards by which people judge desirability, goodness, and beauty, and which serve as broad guidelines for social living as well as public policies

Glossary - English Grammar (A-Z)

2008-03-23T05:49:00.000-07:00

A

Adjectival

Functioning as an adjective. Phrases and clauses that modify nouns are adjectival.

Adjective

A word that modifies the meaning of a noun.

The little girl climbed quickly up the very tall tree.

Adjectives are capable of comparison:

positive: small, beautiful

comparative: smaller, more beautiful

superlative: smallest, most beautiful.

Adverb

A word that modifies the meaning of a verb, an adjective, or another adverb. They answer the questions "how?" "when?" "where?" etc.

The little girl climbed quickly up the very tall tree.

Adverbs are capable of comparison:

positive fast, quickly

comparative faster, more quickly

superlative fastest, most quickly.

Adverbial

Functioning as an adverb. Phrases and clauses that modify verbs, adjectives, and other adverbs are adverbial.

Article

One of a set of three words: the, the definite article; aand an, the two forms of the indefinite article.

Auxiliary

A "helping verb" like "have" or "should" or "was."

I should have been trying to please them, but I forgot.

C

Case

The use of word form to indicate grammatical function. The form "I" identifies the pronoun as either a subject or a subject completion, "my" or "mine" indicates possession, while "me" is the equivalent object form. Noun endings only indicate whether or not the noun is a possessive: Lara, Lara's.

Clause

A group of words containing a complete predication. Clauses belong to two types: (1) subordinate, relative, or dependent clauses (italicised below) function only when conjoined to (2) a main, coordinate, or independent clause, which can--contrariwise--stand by itself.

Before Tanya or I arrived, it had become late and cold, so we left.

Completion

A word or group of words that combine with a verb to complete the meaning of a predicate. Different verbs take different kinds of completions: objects, indirect objects, subject completions.

Complex sentence

A sentence made up of a main clause together with one or more subordinate or relative clauses.

Barb ran down the street for help while Liz called the police.

Compound Sentence

A sentence made up of two or more independent or main clauses.

Liz ran down the street for help and Barb called the police.

Conjunction

One of a small number of relational (function) words that join words or groups of words together. Conjunctions are of two kinds: some like "and," "or," "for," join words or phrases of equivalent grammatical weight.

Before Tanya or I arrived, it had become late and was turning cold, so we left.

Others, like "since," "when," and sometimes "for," connect subordinate clauses to the rest of the sentence.

Before Tanya or I arrived, it had become late and cold, so we left.

Conjunctive Adverb

An adverb expressing a relationship between main clauses, which can be joined by a semi-colon. Unlike a conjunction, a conjunctive adverb need not come between the main clauses:

I worked hard; nevertheless I did no better than before.

I worked hard; I nevertheless did no better than before.

There are entries for these letters:

G

Gender Specificity

The restriction of noun or pronoun reference to male or female persons or animals. "He" and "chairman" exhibit gender specificity: the former is a very odd pronoun to use for a woman; the latter an incongruous noun when used for the same purpose.

Gerund

A verbal that functions as a noun (as distinct from a participle that functions as an adjective). In the following examples, "Running" is a gerund in the first, and a modifying participle in the second.

Running in every race was Amanda's goal.

Running in every race, Amanda was known to everyone.

Grammar

1. The rules by which native speakers generate acceptable sentences in a language. 2. the study or codification of such rules.

H

Hyper-correct

Too correct; so correct as to be wrong.

That's between Jay and I.

I

Infinitive

The non-finite form of a verb, that is, the form of the verb which is not limited to time, place, or agent. A verbal capable of functioning as a noun, or a modifier, or combined with an auxiliary verb to construct a synthetic verb form. Infinitives can have subjects and completions.

To offer help is better than to refuse it.

Friends and neighbours stopped by to offer help after the fire.

I was able to offer help because I was at hand.

Inflectional System

The pattern of endings indicating different cases or numbers in nouns and pronouns, as well as different tenses in verbs:

Subject: he they who it Mary

Possessive: his their(s) whose its Mary's
Object: him them whom it Mary
Tenses:
give, gave, given
tide, rode, ridden
go, went, gone
sit, sat, sat

Interjection

An exclamatory word intended to express strong feelings.

Interrogation

questioning

M

Modifier

A word or group of words that adds to or refines the meaning of another word. Modifiers are either adjectives or adverbs.

Mood

the form of the verb by which it denotes a state (indicative), a command (imperative), a question (interrogative), or a hypothetical condition (subjunctive).

There are entries for these letters:

N

Negation

A denial; the opposite of affirmation

Mark did not sell his store.

Non-restrictive clause

A clause that adds to our knowledge of whatever it is it modifies but without being crucial to its identification; the opposite of restrictive clause.

The children, who loved ice cream, ran to the Dairy Queen.

Noun

The name of a person, place, or thing. A proper belongs to a particular individual; a common noun identifies a member of a group.

Mark sold his store.

O

Object (direct)

The person or thing affected by the action of the verb; a verb completion

Noel hit the ball; it hit me.

Noel hit me the ball.

Object (indirect)

The person or thing indirectly affected by the action of the verb; a verb completion.

Noel hit me the ball.

Object case

The form that certain pronouns take when they are the object in a sentence. (The object case combines the Old English accusative and dative cases, corresponding roughly to the direct and indirect objects noted above.)

P

Participle

One of two different kinds of verb-derived words which can function as nouns, modifiers, or parts of synthetic verbs. Present participles end with "-ing." Past participles of most verbs end with "-ed" or "-en."

I hate running when I feel tired.

He was running scared.

Parts of Speech

The classes of words from which sentences are constructed: nouns, pronouns, adjectives, verbs, adverbs, prepositions, conjunctions, and interjections etc.

Phrase

A unified group of words which does not include both parts of the actor-act combination that produces predication. The term is a general one, but includes the prepositional phrase as one of its most important classes.

In the box which sat on the porch behind the house was an egg.

Plural

more than one; the opposite of singular.

Possessive Case (traditionally called the genetive case)

The form indicating "possession"; it includes but is not restricted to ownership.

Predicate

what is said about the subject. It comprises a verb, which may stand alone, or the entire verb phrase including complements.

Children read.

Friends and neighbours stopped by to offer help after the event.

Grass is green.

Predication

The act of saying something about a subject.

Preposition

One of a small number of relational (function) words like "in," "on," "behind," etc. which are known as prepositions because they are "pre-posed" or "placed before" the phrases they introduce.

In the box which sat on the porch behind the house was an egg.

Pronoun

A word standing for a noun. There are many different kinds of pronouns, including the following: indefinite pronouns ("some," "any"), demonstrative pronouns ("this," "those"), interrogative pronouns ("who," "which"), personal pronouns ("I," "you," "she"),

There are entries for these letters:

R

Relative pronouns

Which, that, whom> and so on.

Restrictive clause

A clause crucial to the identification of whatever it modifies; the opposite of a non-restrictive clause. The restrictive clause is not set off from the rest of the sentence by commas.

Children who are allergic to milk should avoid ice cream.

S

Singular

One; the opposite of plural.

Subject

The word or words in a sentence about which something is said.

Children read.

Friends and neighbours stopped by to offer help after the event.

Subject Case

Traditionally called nominative case) the form that certain pronouns take when they are the subject or subject completion of a sentence.

Iam here.

This is she.

Subject Completion (also called a subjective completion)

Either a noun or an adjective (a predicate nominative or a predicate adjective) that completes a copulative or linking verb by defining or describing its subject.

The ball appeared round.

Ms. Carswell is a lawyer.

Synthetic verb form

A multi-part verb form expressing one of a variety of possible degrees of pastness, futurity, completeness, habitualness, determination, uncertainty or the like.

I should have been trying to please them, but I forgot.

V

Verb

A word which specifies the action or condition in which the subject of a sentence participates. Predicates comprise a verb with whatever modifiers or complements accompany it.

Friends and neighbours stopped by to offer help after the event.

You seem unhappy.

Verbs are capable of being inflected for tense (and number):

stop (stops) stopped stopped

bite (bites) bit bitten

Verb Phrase

The combination of a verb and an adverb whose combined meaning cannot be deduced from their individual meanings.

Friends and neighbours stopped by to offer help after the event.

Compare:

He stopped by the side of the road.

Verbal

A form of a verb which either (1) does not function as a verb but as a noun or adjective or (2) combines with another verb to form a predicate. Infinitives and participles are verbals.

Glossary - Volcanic (A-Z)

2008-03-23T05:24:00.000-07:00

'A'a: Hawaiian word used to describe a lava flow whose surface is broken into rough angular fragments.

Accessory: A mineral whose presence in a rock is not essential to the proper classification of the rock.

Accidental: Pyroclastic rocks that are formed from fragments of non-volcanic rocks or from volcanic rocks not related to the erupting volcano.

Accretionary Lava Ball: A rounded mass, ranging in diameter from a few centimeters to several meters, [carried] on the surface of a lava flow (e.g., 'a'a) or on cinder-cone slopes [and formed] by the molding of viscous lava around a core of already solidified lava.

Acid: A descriptive term applied to igneous rocks with more than 60% silica (SiO2).

Active Volcano: A volcano that is erupting. Also, a volcano that is not presently erupting, but that has erupted within historical time and is considered likely to do so in the future.

Agglutinate: A pyroclastic deposit consisting of an accumulation of originally plastic ejecta and formed by the coherence of the fragments upon solidification.

Alkalic: Rocks which contain above average amounts of sodium and/or potassium for the group of rocks for which it belongs. For example, the basalts of the capping stage of Hawaiian volcanoes are alkalic. They contain more sodium and/or potassium than the shield-building basalts that make the bulk of the volcano.

Andesite: Volcanic rock (or lava) characteristically medium dark in color and containing 54 to 62 percent silica and moderate amounts of iron and magnesium.

Ash: Fine particles of pulverized rock blown from an explosion vent. Measuring less than 1/10 inch in diameter, ash may be either solid or molten when first erupted. By far the most common variety is vitric ash (glassy particles formed by gas bubbles bursting through liquid magma).

Ashfall (Airfall): Volcanic ash that has fallen through the air from an eruption cloud. A deposit so formed is usually well sorted and layered.

Ash Flow: A turbulent mixture of gas and rock fragments, most of which are ash-sized particles, ejected violently from a crater or fissure. The mass of pyroclastics is normally of very high temperature and moves rapidly down the slopes or even along a level surface.

Asthenosphere: The shell within the earth, some tens of kilometers below the surface and of undefined thickness, which is a shell of weakness where plastic movements take place to permit pressure adjustments.

Aquifer: A body of rock that contains significant quantities of water that can be tapped by wells or springs.

Avalanche: A large mass of material or mixtures of material falling or sliding rapidly under the force of gravity. Avalanches often are classified by their content, such as snow, ice, soil, or rock avalanches. A mixture of these materials is a debris avalanche.

Basalt: Volcanic rock (or lava) that characteristically is dark in color, contains 45% to 54% silica, and generally is rich in iron and magnesium.

Basement: The undifferentiated rocks that underlie the rocks of interest in an area.

Basic: A descriptive term applied to igneous rocks (basalt and gabbro) with silica (SiO2) between 44% and 52%.

Bench: The unstable, newly-formed front of a lava delta.

Blister: A swelling of the crust of a lava flow formed by the puffing-up of gas or vapor beneath the flow. Blisters are about 1 meter in diameter and hollow.

Block: Angular chunk of solid rock ejected during an eruption.

Bomb: Fragment of molten or semi-molten rock, 2 1/2 inches to many feet in diameter, which is blown out during an eruption. Because of their plastic condition, bombs are often modified in shape during their flight or upon impact.

Caldera: The Spanish word for cauldron, a basin-shaped volcanic depression; by definition, at least a mile in diameter. Such large depressions are typically formed by the subsidence of volcanoes. Crater Lake occupies the best-known caldera in the Cascades.

Capping Stage: Refers to a stage in the evolution of a typical Hawaiian volcano during which alkalic, basalt, and related rocks build a steeply, sloping cap on the main shield of the volcano. Eruptions are less frequent, but more explosive. The summit caldera may be buried.

Central Vent: A central vent is an opening at the Earth's surface of a volcanic conduit of cylindrical or pipe-like form.

Central Volcano: A volcano constructed by the ejection of debris and lava flows from a central point, forming a more or less symmetrical volcano.

Cinder Cone: A volcanic cone built entirely of loose fragmented material (pyroclastics.)

Cirque: A steep-walled horseshoe-shaped recess high on a mountain that is formed by glacial erosion.

Cleavage: The breaking of a mineral along crystallographic planes, that reflects a crystal structure.

Composite Volcano: A steep volcanic cone built by both lava flows and pyroclastic eruptions.

Compound Volcano: A volcano that consists of a complex of two or more vents, or a volcano that has an associated volcanic dome, either in its crater or on its flanks. Examples are Vesuvius and Mont Pelee.

Compression Waves: Earthquake waves that move like a slinky. As the wave moves to the left, for example, it expands and compresses in the same direction as it moves.

Conduit: A passage followed by magma in a volcano.

Continental Crust: Solid, outer layers of the earth, including the rocks of the continents.

Continental Drift: The theory that horizontal movement of the earth's surface causes slow, relative movements of the continents toward or away from one another.

Country Rocks: The rock intruded by and surrounding an igneous intrusion.

Crater: A steep-sided, usually circular depression formed by either explosion or collapse at a volcanic vent.

Craton: A part of the earth's crust that has attained stability and has been little deformed for a prolonged period.

Curtain of Fire: A row of coalescing lava fountains along a fissure; a typical feature of a Hawaiian-type eruption.

Dacite: Volcanic rock (or lava) that characteristically is light in color and contains 62% to 69% silica and moderate a mounts of sodium and potassium.

Debris Avalanche: A rapid and unusually sudden sliding or flowage of unsorted masses of rock and other material. As applied to the major avalanche involved in the eruption of Mount St. Helens, a rapid mass movement that included fragmented cold and hot volcanic rock, water, snow, glacier ice, trees, and some hot pyroclastic material. Most of the May 18, 1980 deposits in the upper valley of the North Fork Toutle River and in the vicinity of Spirit Lake are from the debris avalanche.

Debris Flow: A mixture of water-saturated rock debris that flows downslope under the force of gravity (also called lahar or mudflow).

Detachment Plane: The surface along which a landslide disconnects from its original position.

Devonian: A period of time in the Paleozoic Era that covered the time span between 400 and 345 million years.

Diatreme: A breccia filled volcanic pipe that was formed by a gaseous explosion.

Dike: A sheetlike body of igneous rock that cuts across layering or contacts in the rock into which it intrudes.

Dome: A steep-sided mass of viscous (doughy) lava extruded from a volcanic vent (often circular in plane view) and spiny, rounded, or flat on top. Its surface is often rough and blocky as a result of fragmentation of the cooler, outer crust during growth of the dome.

Dormant Volcano: Literally, "sleeping." The term is used to describe a volcano which is presently inactive but which may erupt again. Most of the major Cascade volcanoes are believed to be dormant rather than extinct.

Drainage Basin: The area of land drained by a river system.

Echelon: Set of geologic features that are in an overlapping or a staggered arrangement (e.g., faults). Each is relatively short, but collectively they form a linear zone in which the strike of the individual features is oblique to that of the zone as a whole.

Ejecta: Material that is thrown out by a volcano, including pyroclastic material (tephra) and lava bombs.

Episode: An episode is a volcanic event that is distinguished by its duration or style.

Eruption: The process by which solid, liquid, and gaseous materials are ejected into the earth's atmosphere and onto the earth's surface by volcanic activity. Eruptions range from the quiet overflow of liquid rock to the tremendously violent expulsion of pyroclastics.

Eruption Cloud: The column of gases, ash, and larger rock fragments rising from a crater or other vent. If it is of sufficient volume and velocity, this gaseous column may reach many miles into the stratosphere, where high winds will carry it long distances.

Eruptive Vent: The opening through which volcanic material is emitted.

Evacuate: Temporarily move people away from possible danger.

Extinct Volcano: A volcano that is not presently erupting and is not likely to do so for a very long time in the future. Usage of extinct.

Extrusion: The emission of magmatic material at the earth's surface. Also, the structure or form produced by the process (e.g., a lava flow, volcanic dome, or certain pyroclastic rocks).

Fault: A crack or fracture in the earth's surface. Movement along the fault can cause earthquakes or--in the process of mountain-building--can release underlying magma and permit it to rise to the surface.

Fault Scarp A steep slope or cliff formed directly by movement along a fault and representing the exposed surface of the fault before modification by erosion and weathering.

Felsic: An igneous rock having abundant light-colored minerals.

Fire fountain: See also: lava fountain

Fissures: Elongated fractures or cracks on the slopes of a volcano. Fissure eruptions typically produce liquid flows, but pyroclastics may also be ejected.

Flank Eruption: An eruption from the side of a volcano (in contrast to a summit eruption.)

Fluvial: Produced by the action of of flowing water.

Formation: A body of rock identified by lithic characteristics and stratigraphic position and is mappable at the earth's surface or traceable in the subsurface.

Fracture: The manner of breaking due to intense folding or faulting.

Fumarole: A vent or opening through which issue steam, hydrogen sulfide, or other gases. The craters of many dormant volcanoes contain active fumaroles.

Geothermal Energy: Energy derived from the internal heat of the earth.

Geothermal Power: Power generated by using the heat energy of the earth.

Graben: An elongate crustal block that is relatively depressed (downdropped) between two fault systems.

Guyot: A type of seamount that has a platform top. Named for a nineteenth-century Swiss-American geologist.

Hardness: The resistance of a mineral to scratching.

Harmonic Tremor: A continuous release of seismic energy typically associated with the underground movement of magma. It contrasts distinctly with the sudden release and rapid decrease of seismic energy associated with the more common type of earthquake caused by slippage along a fault.

Heat transfer: Movement of heat from one place to another.

Heterolithologic: Material is made up of a heterogeneous mix of different rock types. Instead of being composed on one rock type, it is composed of fragments of many different rocks.

Holocene: The time period from 10,000 years ago to the present. Also, the rocks and deposits of that age.

Horizontal Blast: An explosive eruption in which the resultant cloud of hot ash and other material moves laterally rather than upward.

Horst: A block of the earth's crust, generally long compared to its width, that has been uplifted along faults relative to the rocks on either side.

Hot Spot: A volcanic center, 60 to 120 miles (100 to 200 km) across and persistent for at least a few tens of million of years, that is thought to be the surface expression of a persistent rising plume of hot mantle material. Hot spots are not linked to arcs and may not be associated with ocean ridges.

Hot-spot Volcanoes: Volcanoes related to a persistent heat source in the mantle.

Hyaloclastite: A deposit formed by the flowing or intrusion of lava or magma into water, ice, or water-saturated sediment and its consequent granulation or shattering into small angular fragments.

Hydrothermal Reservoir: An underground zone of porous rock containing hot water.

Hypabyssal: A shallow intrusion of magma or the resulting solidified rock.

Hypocenter: The place on a buried fault where an earthquake occurs.

Ignimbrite: The rock formed by the widespread deposition and consolidation of ash flows and Nuees Ardentes. The term was originally applied only to densely welded deposits but now includes non-welded deposits.

Intensity: A measure of the effects of an earthquake at a particular place. Intensity depends not only on the magnitude of the earthquake, but also on the distance from the epicenter and the local geology.

Intermediate: A descriptive term applied to igneous rocks that are transitional between basic and acidic with silica (SiO2) between 54% and 65%.

Intrusion: The process of emplacement of magma in pre-existing rock. Also, the term refers to igneous rock mass so formed within the surrounding rock.

Joint: A surface of fracture in a rock.

Juvenile: Pyroclastic material derived directly from magma reaching the surface.

Kipuka: An area surrounded by a lava flow.

Laccolith: A body of igneous rocks with a flat bottom and domed top. It is parallel to the layers above and below it.

Lahar: A torrential flow of water-saturated volcanic debris down the slope of a volcano in response to gravity. A type of mudflow.

Landsat: A series of unmanned satellites orbiting at about 706 km (438 miles) above the surface of the earth. The satellites carry cameras similar to video cameras and take images or pictures showing features as small as 30 m or 80 m wide, depending on which camera is used.

Lapilli: Literally, "little stones." Round to angular rock fragments, measuring 1/10 inch to 2 1/2 inches in diameter, which may be ejected in either a solid or molten state.

Lava: Magma which has reached the surface through a volcanic eruption. The term is most commonly applied to streams of liquid rock that flow from a crater or fissure. It also refers to cooled and solidified rock.

Lava Dome: Mass of lava, created by many individual flows, that has built a dome-shaped pile of lava.

Lava Flow: An outpouring of lava onto the land surface from a vent or fissure. Also, a solidified tongue like or sheet-like body formed by outpouring lava.

Lava Fountain: A rhythmic vertical fountainlike eruption of lava.

Lava Lake (Pond): A lake of molten lava, usually basaltic, contained in a vent, crater, or broad depression of a shield volcano.

Lava Shields: A shield volcano made of basaltic lava.

Lava Tube: A tunnel formed when the surface of a lava flow cools and solidifies while the still-molten interior flows through and drains away.

Limu O Pele (Pele Seaweed): Delicate, translucent sheets of spatter filled with tiny glass bubbles.

Lithic: Of or pertaining to stone.

Lithosphere: The rigid crust and uppermost mantle of the earth. Thickness is on the order of 60 miles (100 km). Stronger than the underlying asthenosphere.

Luster: The reflection of light from the surface of a mineral.

Maar: A volcanic crater that is produced by an explosion in an area of low relief, is generally more or less circular, and often contains a lake, pond, or marsh.

Mafic: An igneous composed chiefly of one or more dark-colored minerals.

Magma: Molten rock beneath the surface of the earth.

Magma Chamber: The subterranean cavity containing the gas-rich liquid magma which feeds a volcano.

Magmatic: Pertaining to magma.

Magnitude: A numerical expression of the amount of energy released by an earthquake, determined by measuring earthquake waves on standardized recording instruments (seismographs.) The number scale for magnitudes is logarithmic rather than arithmetic. Therefore, deflections on a seismograph for a magnitude 5 earthquake, for example, are 10 times greater than those for a magnitude 4 earthquake, 100 times greater than for a magnitude 3 earthquake, and so on.

Mantle: The zone of the earth below the crust and above the core.

Matrix: The solid matter in which a fossil or crystal is embedded. Also, a binding substance (e.g., cement in concrete).

Miocene: An epoch in Earth's history from about 24 to 5 million years ago. Also refers to the rocks that formed in that epoch.

Moho: Also called the Mohorovicic discontinuity. The surface or discontinuity that separates the crust from the mantle. The Moho is at a depth of 5-10 km beneath the ocean floor and about 35 km below the continents (but down to 60 km below mountains). Named for Andrija Mohorovicic, a Croatian seismologist.

Monogenetic: A volcano built by a single eruption.

Mudflow: A flowage of water-saturated earth material possessing a high degree of fluidity during movement. A less-saturated flowing mass is often called a debris flow. A mudflow originating on the flank of a volcano is properly called a lahar.

Myth: A fictional story to explain the origin of some person, place, or thing.

Nuees Ardentes: A French term applied to a highly heated mass of gas-charged ash which is expelled with explosive force and moves hurricane speed down the mountainside.

Obsidian: A black or dark-colored volcanic glass, usually composed of rhyolite.

Oceanic Crust: The earth's crust where it underlies oceans.

Pahoehoe: A Hawaiian term for lava with a smooth, billowy, or ropy surface.

Pali: Hawaiian word for steep hills or cliffs.

Pele Hair: A natural spun glass formed by blowing-out during quiet fountaining of fluid lava, cascading lava falls, or turbulent flows, sometimes in association with pele tears. A single strand, with a diameter of less than half a millimeter, may be as long as two meters.

Pele Tears: Small, solidified drops of volcanic glass behind which trail pendants of Pele hair. They may be tear-shaped, spherical, or nearly cylindrical.

Peralkaline: Igneous rocks in which the molecular proportion of aluminum oxide is less than that of sodium and potassium oxides combined.

Phenocryst: A conspicuous, usually large, crystal embedded in porphyritic igneous rock.

Phreatic Eruption (Explosion): An explosive volcanic eruption caused when water and heated volcanic rocks interact to produce a violent expulsion of steam and pulverized rocks. Magma is not involved.

Phreatomagmatic: An explosive volcanic eruption that results from the interaction of surface or subsurface water and magma.

Pillow lava: Interconnected, sack-like bodies of lava formed underwater.

Pipe: A vertical conduit through the Earth's crust below a volcano, through which magmatic materials have passed. Commonly filled with volcanic breccia and fragments of older rock.

Pit Crater: A crater formed by sinking in of the surface, not primarily a vent for lava.

Plastic: Capable of being molded into any form, which is retained.

Plate Tectonics: The theory that the earth's crust is broken into about 10 fragments (plates,) which move in relation to one another, shifting continents, forming new ocean crust, and stimulating volcanic eruptions.

Pleistocene: A epoch in Earth history from about 2-5 million years to 10,000 years ago. Also refers to the rocks and sediment deposited in that epoch.

Plinian Eruption: An explosive eruption in which a steady, turbulent stream of fragmented magma and magmatic gases is released at a high velocity from a vent. Large volumes of tephra and tall eruption columns are characteristic.

Plug: Solidified lava that fills the conduit of a volcano. It is usually more resistant to erosion than the material making up the surrounding cone, and may remain standing as a solitary pinnacle when the rest of the original structure has eroded away.

Plug Dome: The steep-sided, rounded mound formed when viscous lava wells up into a crater and is too stiff to flow away. It piles up as a dome-shaped mass, often completely filling the vent from which it emerged.

Pluton: A large igneous intrusion formed at great depth in the crust.

Polygenetic: Originating in various ways or from various sources.

Precambrian:All geologic time from the beginning of Earth history to 570 million years ago. Also refers to the rocks that formed in that epoch.

Pumice: Light-colored, frothy volcanic rock, usually of dacite or rhyolite composition, formed by the expansion of gas in erupting lava. Commonly seen as lumps or fragments of pea-size and larger, but can also occur abundantly as ash-sized particles.

Pyroclastic: Pertaining to fragmented (clastic) rock material formed by a volcanic explosion or ejection from a volcanic vent.

Pyroclastic Flow: Lateral flowage of a turbulent mixture of hot gases and unsorted pyroclastic material (volcanic fragments, crystals, ash, pumice, and glass shards) that can move at high speed (50 to 100 miles an hour.) The term also can refer to the deposit so formed.

Quaternary: The period of Earth's history from about 2 million years ago to the present; also, the rocks and deposits of that age.

Relief: The vertical difference between the summit of a mountain and the adjacent valley or plain.

Renewed Volcanism State: Refers to a state in the evolution of a typical Hawaiian volcano during which --after a long period of quiescence--lava and tephra erupt intermittently. Erosion and reef building continue.

Repose: The interval of time between volcanic eruptions.

Rhyodacite: An extrusive rock intermediate in composition between dacite and rhyolite.

Rhyolite: Volcanic rock (or lava) that characteristically is light in color, contains 69% silica or more, and is rich in potassium and sodium.

Ridge, Oceanic: A major submarine mountain range.

Rift System: The oceanic ridges formed where tectonic plates are separating and a new crust is being created; also, their on-land counterparts such as the East African Rift.

Rift Zone: A zone of volcanic features associated with underlying dikes. The location of the rift is marked by cracks, faults, and vents.

Ring of Fire: The regions of mountain-building earthquakes and volcanoes which surround the Pacific Ocean.

Scoria: A bomb-size (> 64 mm) pyroclast that is irregular in form and generally very vesicular. It is usually heavier, darker, and more crystalline than pumice.

Seafloor Spreading: The mechanism by which new seafloor crust is created at oceanic ridges and slowly spreads away as plates are separating.

Seamount: A submarine volcano.

Seismograph: An instrument that records seismic waves; that is, vibrations of the earth.

Seismologist: Scientists who study earthquake waves and what they tell us about the inside of the Earth.

Seismometer: An instrument that measures motion of the ground caused by earthquake waves.

Shearing: The motion of surfaces sliding past one another.

Shear Waves: Earthquake waves that move up and down as the wave itself moves. For example, to the left.

Shield Volcano: A gently sloping volcano in the shape of a flattened dome and built almost exclusively of lava flows.

Shoshonite: A trachyandesite composed of olivine and augite phenocrysts in a groundmass of labradorite with alkali feldspar rims, olivine, augite, a small amount of leucite, and some dark-colored glass. Its name is derived from the Shoshone River, Wyoming and given by Iddings in 1895.

Silica: A chemical combination of silicon and oxygen.

Sill: A tabular body of intrusive igneous rock, parallel to the layering of the rocks into which it intrudes.

Skylight: An opening formed by a collapse in the roof of a lava tube.

Solfatara: A type of fumarole, the gases of which are characteristically sulfurous.

Spatter Cone: A low, steep-sided cone of spatter built up on a fissure or vent. It is usually of basaltic material.

Spatter Rampart: A ridge of congealed pyroclastic material (usually basaltic) built up on a fissure or vent.

Specific Gravity: The density of a mineral divided by the density of water.

Spines: Horn-like projections formed upon a lava dome.

Stalactite: A cone shaped deposit of minerals hanging from the roof of a cavern.

Stratigraphic: The study of rock strata, especially of their distribution, deposition, and age.

Stratovolcano:A volcano composed of both lava flows and pyroclastic material.

Streak: The color of a mineral in the powdered form.

Strike-Slip Fault: A nearly vertical fault with side-slipping displacement.

Strombolian Eruption: A type of volcanic eruption characterized by jetting of clots or fountains of fluid basaltic lava from a central crater.

Subduction Zone: The zone of convergence of two tectonic plates, one of which usually overrides the other.

Surge: A ring-shaped cloud of gas and suspended solid debris that moves radially outward at high velocity as a density flow from the base of a vertical eruption column accompanying a volcanic eruption or crater formation.

Talus: A slope formed a the base of a steeper slope, made of fallen and disintegrated materials.

Tephra: Materials of all types and sizes that are erupted from a crater or volcanic vent and deposited from the air.

Tephrochronology: The collection, preparation, petrographic description, and approximate dating of tephra.

Tilt: The angle between the slope of a part of a volcano and some reference. The reference may be the slope of the volcano at some previous time.

Trachyandesite: An extrusive rock intermediate in composition between trachyte and andesite.

Trachybasalt: An extrusive rock intermediate in composition between trachyte and basalt.

Trachyte: A group of fine-grained, generally porphyritic, extrusive igneous rocks having alkali feldspar and minor mafic minerals as the main components, and possibly a small amount of sodic plagioclase.

Tremor: Low amplitude, continuous earthquake activity often associated with magma movement.

Tsunami: A great sea wave produced by a submarine earthquake, volcanic eruption, or large landslide.

Tuff: Rock formed of pyroclastic material.

Tuff Cone: A type of volcanic cone formed by the interaction of basaltic magma and water. Smaller and steeper than a tuff ring.

Tuff Ring: A wide, low-rimmed, well-bedded accumulation of hyalo-clastic debris built around a volcanic vent located in a lake, coastal zone, marsh, or area of abundant ground water.

Tumulus: A doming or small mound on the crest of a lava flow caused by pressure due to the difference in the rate of flow between the cooler crust and the more fluid lava below.

Ultramafic: Igneous rocks made mostly of the mafic minerals hypersthene, augite, and/or olivine.

Unconformity: A substantial break or gap in the geologic record where a rock unit is overlain by another that is not next in stratigraphic sucession, such as an interruption in continuity of a depositional sequence of sedimentary rocks or a break between eroded igneous rocks and younger sedimentary strata. It results from a change that caused deposition to cease for a considerable time, and it normally implies uplift and erosion with loss of the previous formed record.

Vent: The opening at the earth's surface through which volcanic materials issue forth.

Vesicle: A small air pocket or cavity formed in volcanic rock during solidification.

Viscosity: A measure of resistance to flow in a liquid (water has low viscosity while honey has a higher viscosity.)

Volcano: A vent in the surface of the Earth through which magma and associated gases and ash erupt; also, the form or structure (usually conical) that is produced by the ejected material.

Volcanic Arc: A generally curved linear belt of volcanoes above a subduction zone, and the volcanic and plutonic rocks formed there.

Volcanic Complex: A persistent volcanic vent area that has built a complex combination of volcanic landforms.

Volcanic Cone: A mound of loose material that was ejected ballistically.

Volcanic Neck: A massive pillar of rock more resistant to erosion than the lavas and pyroclastic rocks of a volcanic cone.

Vulcan: Roman god of fire and the forge after whom volcanoes are named.

Vulcanian: A type of eruption consisting of the explosive ejection of incandescent fragments of new viscous lava, usually on the form of blocks.

Water Table: The surface between where the pore space in rock is filled with water and where the the pore space in rock is filled with air.

Xenocrysts: A crystal that resembles a phenocryst in igneous rock, but is a foreign to the body of rock in which it occurs.

Xenoliths: A foreign inclusion in an igneous rock.

Glossary - Geology (W-Z)

2008-03-23T05:13:00.000-07:00

watershed

See drainage basin.

water table

The surface that lies between the zone of aeration and the underlying zone of saturation.

wave-cut bench

A relatively level surface formed when waves erode the base of a cliff, causing the overlying rock to fall into the surf. A wave-cut bench stands above the water and extends seaward from what remains of the cliff.

wave refraction

The process by which a wave approaching the shore changes direction due to slowing of those parts of the wave that enter shallow water first, causing a sharp decrease in the angle at which the wave approaches until the wave is almost parallel to the coast.

weathering

The process by which exposure to atmospheric agents, such as air or moisture, causes rocks and minerals to break down. This process takes place at or near the Earth's surface. Weathering entails little or no movement of the material that it loosens from the rocks and minerals. See also erosion.

welded tuff

A volcanic igneous rock that forms when still-warm tephra accumulates at the Earth's surface. Because the particles are still warm and soft, they can weld together under the weight of overlying deposits, forming a hard rock.

wetland

A lake, marsh, or swamp that supports wildlife and replenishes the groundwater system.

wind abrasion

The process by which wind erodes bedrock through contact between the bedrock and rock particles carried by the wind.

xenolith

A preexisting rock embedded in a newer igneous rock. Xenoliths are formed when a rising magma incorporates the preexisting rock. If the preexisting rock does not melt, it will not be assimilated into the magma and will therefore remain distinct from the new igneous rock that surrounds it.

X-ray diffraction

The scattering of X rays passed through a mineral sample so as to form a pattern peculiar to the given mineral.

yield point

The maximum stress that a given rock can withstand without becoming permanently deformed

zone of ablation

The part of a glacier in which there is greater overall loss than gain in volume. A zone of ablation can be identified in the summer by an expanse of bare ice. See also zone of accumulation.

zone of accumulation

The part of a glacier in which there is greater overall gain than loss in volume. A zone of accumulation can be identified by a blanket of snow that survives summer melting. See also zone of ablation.

zone of aeration

A region below the Earth's surface that is marked by the presence of both water and air in the pores of rocks and soil. Also called aeration zone.

zone of saturation

A region that lies below the zone of aeration and is marked by the presence of water and the absence of air in the pores of rocks and soil.

Glossary - Geology (U-V)

2008-03-23T05:12:00.001-07:00

unconformity

A boundary separating two or more rocks of markedly different ages, marking a gap in the geologic record.

uniformitarianism

The hypothesis that current geologic processes, such as the slow erosion of a coast under the impact of waves, have been occurring in a similar manner throughout the Earth's history and that these processes can account for past geologic events. See also catastrophism.

upwarped mountain

A mountain consisting of a broad area of the Earth's crust that has moved gently upward without much apparent deformation, and usually containing sedimentary, igneous, and metamorphic rocks.

uranium-thorium-lead dating

A form of isotope dating that relies on the extremely long half-life of radioactive isotopes of uranium, which decay into isotopes of lead, to determine the age of rocks in which uranium and lead are present.

valley glacier

An alpine glacier that flows through a preexisting stream valley.

van der Waals bond

A relatively weak kind of intermolecular bond that forms when one side of a molecule develops a slight negative charge because a number of electrons have temporarily moved to that side of the molecule. This negative charge attracts the nuclei of the atoms of a neighboring molecule. The side of the molecule with fewer electrons develops a slight positive charge that attracts the electrons of the atoms of neighboring molecules.

varve

A pair of sediment beds deposited by a lake on its floor, typically consisting of a thick, coarse, light-colored bed deposited in the summer and a thin, fine-grained, dark-colored bed deposited in the winter. Varves are most often found in lakes that freeze in the winter. The number and nature of varves on the bottom of a lake provide information about the lake's age and geologic events that affected the lake's development.

vent

An opening in the Earth's surface through which lava, gases, and hot particles are expelled. Also called volcanic vent and volcano.

ventifact

A stone that has been flattened and sharpened by wind abrasion. Ventifacts are commonly found strewn across a desert floor.

viscosity

A fluid's resistance to flow. Viscosity increases as temperatures decrease.

volcanic arc

A chain of volcanoes fueled by magma that rises from an underlying subducting plate.

volcanic cone

A cone-shaped mountain that forms around a vent from the debris of pyroclastics and lava ejected by numerous eruptions over time.

volcanic crater

A steep, bowl-shaped depression surrounding a vent. A volcanic crater forms when the walls of a vent collapse inward following an eruption.

volcanic dome

A bulb-shaped solid that forms over a vent when lava so viscous that it cannot flow out of the volcanic crater cools and hardens. When a volcanic dome forms, it traps the volcano's gases beneath it. They either escape along a side vent of the volcano or build pressure that causes another eruption and shatters the volcanic dome.

volcanic rock

See extrusive rock.

volcanism

The set of geological processes that result in the expulsion of lava, pyroclastics, and gases at the Earth's surface.

volcano

The solid structure created when lava, gases, and hot particles escape to the Earth's surface through vents. Volcanoes are usually conical. A volcano is "active" when it is erupting or has erupted recently. Volcanoes that have not erupted recently but are considered likely to erupt in the future are said to be "dormant." A volcano that has not erupted for a long time and is not expected to erupt in the future is "extinct."

Glossary - Geology (T)

2008-03-23T05:11:00.001-07:00

talus

A pile of rock fragments lying at the bottom of the cliff or steep slope from which they have broken off.

talus slope

The large pile of rocky boulders that accumulates at the foot of a cliff, typically by the mechanical-weathering process of frost-wedging.

tarn

A deep, typically circular lake that forms when a cirque glacier melts.

tectonic creep

The almost constant movement of certain fault blocks that allows strain energy to be released without major earthquakes.

tension

Stress that stretches or extends rocks, so that they become thinner vertically and longer laterally. Tension may be caused by divergence or rifting.

tephra (plural noun)

Pyroclastic materials that fly from an erupting volcano through the air before cooling, and range in size from fine dust to massive blocks.

terminus

The outer margin of a glacier.

theory

A comprehensive explanation of a given set of data that has been repeatedly confirmed by observation and experimentation and has gained general acceptance within the scientific community but has not yet been decisively proven. See also hypothesis and scientific law.

thermal contraction

A form of mechanical weathering in which cold causes a mineral's crystal structure to contract.

thermal expansion

A form of mechanical weathering in which heat causes a mineral's crystal structure to enlarge.

thermal plume

A vertical column of upwelling mantle material, 100 to 250 kilometers in diameter, that rises from beneath a continent or ocean and can be perceived at the Earth's surface as a hot spot. Thermal plumes carry enough energy to move a plate, and they may be found both at plate boundaries and plate interiors.

thrust fault

A reverse fault marked by a dip of 45º or less.

tidal bore

A turbulent, abrupt, wall-like wave that is caused by a flood tide.

tide

1. The cycle of alternate rising and falling of the surface of an ocean or large lake, caused by the gravitational pull of the Sun and especially Moon in interaction with the Earth's rotation. Tides occur on a regular basis, twice every day on most of the Earth. 2. A single rise or fall within this cycle.

topography

The set of physical features, such as mountains, valleys, and the shapes of landforms, that characterizes a given landscape.

transform motion

The movement of two adjacent lithospheric plates in opposite directions along a parallel line at their common edge. Transform motion often causes earthquakes.

transition zone

The seismic discontinuity located in the upper mantle just beneath the asthenosphere and characterized by a marked increase in the velocity of seismic waves.

translatory motion

the movement of water over a significant distance in the direction of a wave.

transverse dune

One of a series of dunes having an especially steep slip face and a gentle windward slope and standing perpendicular to the prevailing wind direction and parallel to each other. Transverse dunes typically form in arid and semi-arid regions with plentiful sand, stable wind direction, and scarce vegetation. A transverse dune may be as much as 100 kilometers long, 200 meters high, and 3 kilometers wide.

tributary

A stream that supplies water to a larger stream.

trunk stream

A large stream into which tributaries carry water and sediment.

tsunami(plural tsunami)

A vast sea wave caused by the sudden dropping or rising of a section of the sea floor following an earthquake. Tsunami may be as much as 30 meters high and 200 kilometers long, may move as fast as 250 kilometers per hour, and may continue to occur for as long as a few days.

Glossary - Geology (S)

2008-03-23T05:10:00.000-07:00

sandstone

A clastic rock composed of particles that range in diameter from 1/16 millimeter to 2 millimeters in diameter. Sandstones make up about 25% of all sedimentary rocks.

scarp

The steep cliff face that is formed by a slump.

schist

A coarse-grained, strongly foliated metamorphic rock that develops from phyllite and splits easily into flat, parallel slabs.

scientific law

1. A natural phenomenon that has been proven to occur invariably whenever certain conditions are met. 2. A formal statement describing such a phenomenon and the conditions under which it occurs. Also called law.

scientific methods

Techniques that involve gathering all available data on a subject, forming a hypothesis to explain the data, conducting experiments to test the hypothesis, and modifying or confirming the hypothesis as necessary to account for the experimental results.

sea arch

A landform produced by coastal erosion of a prominent headland. Sea arches form when sea caves are excavated so deeply by crashing waves that two caves eroding on opposite sides of the headland become joined. The overlying rocky roof is left as an arch.

sea cave

The notches in the sides of a prominent coastal rocky headland eroded by crahing waves.

sea-floor spreading

The formation and growth of oceans that occurs following rifting and is characterized by eruptions along mid-ocean ridges, forming new oceanic lithosphere, and expanding ocean basins. See also divergence.

seamount

A conical underwater mountain formed by a volcano and rising 1000 meters or more from the sea floor.

sea stack

A steep, isolated island of rock, separated from a headland by the action of waves, as when the overhanging section of a sea arch is eroded.

seawall

A wall of stone, concrete, or other sturdy material, built along the shoreline to prevent erosion even by the strongest and highest of waves. See also riprap.

secondary coast

A coast shaped primarily by erosion or deposition by sea currents and waves.

secondary enrichment

The process by which a metal deposit becomes concentrated when other minerals are eliminated from the deposit, as through dissolution, precipitation, or weathering.

sediment

A collection of transported fragments or precipitated materials that accumulate, typically in loose layers, as of sand or mud.

sedimentary environment

The continental, oceanic, or coastal surroundings in which sediment accumulates.

sedimentary facies

1. A set of characteristics that distinguish a given section of sedimentary rock from nearby sections. Such characteristics include mineral content, grain size, shape, and density. 2. A section of sedimentary rock so characterized.

sedimentary rock

A rock made from the consolidation of solid fragments, as of other rocks or organic remains, or by precipitation of minerals from solution.

sedimentary structure

A physical characteristic of a detrital sediment that reflects the conditions under which the sediment was deposited.

seismic gap

A locked fault segment that has not experienced seismic activity for a long time. Because stress tends to accumulate in seismic gaps, they often become the sites of major earthquakes.

seismic moment

A numerical means of measuring an earthquake's total energy release. It is calculated by measuring the total length of fault rupture and then factoring in the depth of rupture, total slip along the rupture, and the strength of the faulted rocks.

seismic profiling

The mapping of rocks lying along and beneath the ocean floor by recording the reflections and refractions of seismic waves.

seismic tomography

The process whereby a computer first synthesizes data on the velocities of seismic waves from thousands of recent earthquakes to make a series of images depicting successive planes within the Earth, and then uses these images to construct a three-dimensional representation of the Earth's interior.

seismic wave

One of a series of progressive disturbances that reverberate through the Earth to transmit the energy released from an earthquake.

seismogram

A visual record produced by a seismograph and showing the arrival times and magnitudes of various seismic waves.

seismograph

A machine for measuring the intensity of earthquakes by recording the seismic waves that they generate.

seismology

The study of earthquakes and the structure of the Earth, based on data from seismic waves.

shale

A sedimentary rock composed of detrital sediment particles less than 0.004 millimeter in diameter. Shales tend to be red, brown, black, or gray, and usually originate in relatively still waters.

shearing stress

Stress that slices rocks into parallel blocks that slide in opposite directions along their adjacent sides. Shearing stress may be caused by transform motion.

shield volcano

A low, broad, gently sloping, dome-shaped structure that forms over time as repeated eruptions eject basaltic lava through one or more vents and the lava solidifies in approximately the same volume all around.

shock metamorphism

The metamorphism that results when a meteorite strikes rocks at the Earth's surface. The meteoric impact generates tremendous pressure and extremely high temperatures that cause minerals to shatter and recrystallize, producing new minerals that cannot arise under any other circumstances.

shoreline

The boundary between a body of water and dry land.

silicate

One of several rock-forming minerals that contain silicon, oxygen, and usually one or more other common elements.

silicon oxygen tetrahedron

A four-sided geometric form created by the tight bonding of four oxygen atoms to each other, and also to a single silicon atom that lies in the middle of the form.

sill

A concordant pluton that is substantially wider than it is thick. Sills form within a few kilometers of the Earth's surface. See also dike.

sinkhole

A circular, often funnel-shaped depression in the ground that forms when soluble rocks dissolve.

slate

A fine-grained, foliated metamorphic rock that develops from shale and tends to break into thin, flat sheets.

slide

The mass movement of a single, intact mass of rock, soil, or unconsolidated material along a weak plane, such as a fault, fracture, or bedding plane. A slide may involve as little as a minor displacement of soil or as much as the displacement of an entire mountainside.

slip face

The steep leeward slope of a dune.

slip plane

A weak plane in a rock mass from which material is likely to break off in a slide.

slump

1. A downward and outward slide occurring along a concave slip plane. 2. The material that breaks off in such a slide.

snowline

The lowest point at which snow remains year-round.

soil

The top few meters of regolith, generally including some organic matter derived from plants.

soil horizon

A layer of soil that can be distinguished from the surrounding soil by such features as chemical composition, color, and texture.

soil profile

A vertical strip of soil stretching from the surface down to the bedrock and including all of the successive soil horizons.

solifluction

A form of creep in which soil flows downslope at a rate of 0.5 to 15 centimeters per year. Solifluction occurs in relatively cold regions when the brief warmth of summer thaws only the upper meter or two of regolith, which becomes waterlogged because the underlying ground remains frozen and therefore the water cannot drain down into it.

sorting

The process by which a given transport medium separates out certain particles, as on the basis of size, shape, or density.

source rock

A rock in which hydrocarbons originate.

specific gravity

The ratio of the weight of a particular volume of a given substance to the weight of an equal volume of pure water.

speleothem

A mineral deposit of calcium carbonate that precipitates from solution in a cave.

spheroidal weathering

The process by which chemical weathering, especially by water, decomposes the angles and edges of a rock or boulder, leaving a rounded form from which concentric layers are then stripped away as the weathering continues.

spit

A narrow, fingerlike ridge of sand that extends from land into open water.

stalactite

An icicle-like mineral formation that hangs from the ceiling of a cave and is usually made up of travertine, which precipitates as water rich in dissolved limestone drips down from the cave's ceiling. See also stalagmite.

stalagmite

A cone-shaped mineral deposit that forms on the floor of a cave and is usually made up of travertine, which precipitates as water rich in dissolved limestone drips down from the cave's ceiling. See also stalactite.

star dune

A dune with three or four arms radiating from its usually higher center so that it resembles a star in shape. Star dunes form when winds blow from three or four directions, or when the wind direction shifts frequently.

strain

The change in the shape or volume of a rock that results from stress.

stratovolcano

A cone-shaped volcano built from alternating layers of pyroclastics and viscous andesitic lava. Stratovolcanos tend to be very large and steep.

streak

The color of a mineral in its powdered form. This color is usually determined by rubbing the mineral against an unglazed porcelain slab and observing the mark made by it on the slab.

stream

A body of water found on the Earth's surface and confined to a narrow topographic depression, down which it flows and transports rock particles, sediment, and dissolved particles. Rivers, creeks, brooks, and runs are all streams.

stream discharge

The volume of water to pass a given point on a stream bank per unit of time, usually expressed in cubic meters of water per second.

stream terrace

A level plain lying above and running parallel to a stream bed. A stream terrace is formed when a stream's bed erodes to a substantially lower level, leaving its floodplain high above it.

stress

The force acting on a rock or another solid to deform it, measured in kilograms per square centimeter or pounds per square inch.

striation

One of a group of usually parallel scratches engraved in bedrock by a glacier or other geological agent.

strike 1.

The horizontal line marking the intersection between the inclined plane of a solid geological structure and the Earth's surface. 2. The compass direction of this line, measured in degrees from true north.

strike-slip fault

A fault in which two sections of rock have moved horizontally in opposite directions, parallel to the line of the fracture that divided them. Strike-slip faults are caused by shearing stress.

structural geology

The scientific study of the geological processes that deform the Earth's crust and create mountains.

subduction

The sinking of an oceanic plate edge as a result of convergence with a plate of lesser density. Subduction often causes earthquakes and creates volcano chains.

subsidence

The lowering of the Earth's surface, caused by such factors as compaction, a decrease in groundwater, or the pumping of oil.

sulfate

One of several minerals containing positive sulfur ions bonded to negative oxygen ions.

sulfide

One of several minerals containing negative sulfur ions bonded to one or more positive metallic ions.

surface wave

One of a series of seismic waves that transmits energy from an earthquake's epicenter along the Earth's surface. See also body wave.

surge

To flow more rapidly than usually. Said of a glacier.

suspended load

A body of fine, solid particles, typically of sand, clay, and silt, that travels with stream water without coming in contact with the stream bed.

suture zone

The area where two continental plates have joined together through continental collision. Suture zones are marked by extremely high mountain ranges, such as the Himalayas and the Alps.

S wave (abbreviation for secondary wave)

A body wave that causes the rocks along which it passes to move up and down perpendicular to the direction of its own movement. See also P wave.

S-wave shadow zone

The region within an arc of 154° directly opposite an earthquake's epicenter that is marked by the absence of S waves. The S-wave shadow zone is due to the fact that S waves cannot penetrate the liquid outer core. See also P-wave shadow zone.

syncline

A concave fold, the central part of which contains the youngest section of rock. See also anticline.

Glossary - Geology (Q-R)

2008-03-23T05:08:00.000-07:00

quartzite

An extremely durable, nonfoliated metamorphic rock derived from pure sandstone and consisting primarily of quartz.

quaternary ice age

An ice age that began approximately 1.6 million years ago and continues to the present time.

quick clay

Sediment that sets off a sudden mudflow by changing rapidly from solid to liquid form, as after an earthquake, an explosion, or thunder.

rain shadow effect

The result of the process by which moist air on the windward side of a mountain rises and cools, causing precipitation and leaving the leeward side of the mountain dry.

recrystallization

The diagenetic process by which unstable minerals in buried sediment are transformed into stable ones.

regional metamorphism

Metamorphism that affects rocks over vast geographic areas stretching for thousands of square kilometers.

relative dating

The fixing of a geologic structure or event in a chronological sequence relative to other geologic structures or events. See also numerical dating.

reserve

A known resource that can be exploited for profit with available technology under existing political and economic conditions.

reservoir rock

A permeable rock containing oil or gas.

resource

A mineral or fuel deposit, known or not yet discovered, that may be or become available for human exploitation.

reverse fault

A dip-slip fault marked by a hanging wall that has moved upward relative to the footwall. Reverse faults are often caused by the convergence of lithospheric plates.

rhyolite

Any of a group of felsic igneous rocks that are the extrusive equivalents of granite.

richter scale

A logarithmic scale that measures the amount of energy released during an earthquake on the basis of the amplitude of the highest peak recorded on a seismogram. Each unit increase in the Richter scale represents a 10-fold increase in the amplitude recorded on the seismogram and a 30-fold increase in energy released by the earthquake. Theoretically the Richter scale has no upper limit, but the yield point of the Earth's rocks imposes an effective limit between 9.0 and 9.5.

rifting

The tearing apart of a plate to form a depression in the Earth's crust and often eventually separating the plate into two or more smaller plates.

rip current

A strong, rapid, and brief current that flows out to sea, moving perpendicular to the shoreline.

ripple marks

A pattern of wavy lines formed along the top of a bed by wind, water currents, or waves.

riprap

A pile of large, angular boulders built seaward of the shoreline to prevent erosion by waves or currents. See also seawall.

rock

A naturally formed aggregate of usually inorganic materials from within the Earth.

rock cycle

A series of events through which a rock changes, over time, between igneous, sedimentary, and metamorphic forms.

rock-forming mineral

One of the 20 or so minerals contained in the rock that composes the Earth's crust and mantle.

rubidium-strontium dating

A form of radiometric dating that relies on the 47-billion-year half-life of radioactive isotopes of rubidium, which decay into isotopes of strontium, to determine the age of rocks in which strontium is present. Rubidium-strontium dating is used for rocks that are at least 10 million years old, deep-Earth plutonic rocks, and Moon rocks.

Glossary - Geology (P)

2008-03-23T05:06:00.000-07:00

paleomagnetism

1. The fixed orientation of a rock's crystals, based on the Earth's magnetic field at the time of the rock's formation, that remains constant even when the magnetic field changes. 2. The study of such phenomena as indicators of the Earth's magnetic history.

paleosol

An ancient, buried soil whose composition may reflect a climate significantly different from the climate now prevalent in the area where the soil is found.

Paleozoic Era

The earliest era of the Phanerozoic Eon, marked by the presence of marine invertebrates, fish, amphibians, insects, and land plants.

parabolic dune

A horseshoe-shaped dune having a concave windward slope and a convex leeward slope. Parabolic dunes tend to form along sandy ocean and lake shores. They may also develop from transverse dunes through deflation.

parent isotope

A radioactive isotope that changes into a different isotope when its nucleus decays. See also daughter isotope.

parent material

The source from which a given soil is chiefly derived, generally consisting of bedrock or sediment.

partial melting

The incomplete melting of a rock composed of minerals with differing melting points. When partial melting occurs, the minerals with higher melting points remain solid while the minerals whose melting points have been reached turn to magma.

passive continental margin

A border that lies between continental and oceanic lithosphere, but is not a plate margin. It is marked by lack of seismic and volcanic activity.

peat

A soft brown mass of compressed, partially decomposed vegetation that forms in a water-saturated environment and has a carbon content of 50%. Dried peat can be burned as fuel.

pediment

A broad surface at the base of a receding mountain. The pediment develops when running water erodes most of the mass of the mountain.

pegmatite

A coarse-grained igneous rock with exceptionally large crystals, formed from a magma that contains a high proportion of water.

perched water table

A saturated area that lies within a zone of aeration.

peridotite

An igneous rock composed primarily of the iron-magnesium silicate olivine and having a silica content of less than 40%.

permafrost

Permanently frozen regolith, ranging in thickness from 30 centimeters to over 1000 meters.

permeability

The capability of a given substance to allow the passage of a fluid. Permeability depends on the size of and the degree of connection among a substance's pores.

petroleum

Any of a group of naturally occurring substances made up of hydrocarbons. These substances may be gaseous, liquid, or semi-solid.

phosphorescence

Emission of visible light by a substance, such as a mineral, that is exposed to ultraviolet light and absorbs radiation from it. The light appears in the form of glowing, distinctive colors. The emission continues after the exposure to ultraviolet light ends.

phyllite

A foliated metamorphic rock that develops from slate and is marked by a silky sheen and medium grain size.

placer deposit

A deposit of heavy or durable minerals, such as gold or diamonds, typically found where the flow of water abruptly slows.

plastic deformation

A permanent strain that entails no rupture.

plate tectonics

The theory that the Earth's lithosphere consists of large, rigid plates that move horizontally in response to the flow of the asthenosphere beneath them, and that interactions among the plates at their borders cause most major geologic activity, including the creation of oceans, continents, mountains, volcanoes, and earthquakes.

playa

A dry lake basin found in a desert.

Pleistocene Epoch

The first epoch of the Quaternary Period, beginning 2 to 3 million years ago and ending approximately 10,000 years ago. See also Holocene Epoch.

pluton

An intrusive rock, as distinguished from the preexisting country rock that surrounds it.

plutonic rock

An intrusive rock formed inside the Earth.

pluvial lake

A lake that formed from rainwater falling into a landlocked basin during a glacial period marked by greater precipitation than is found in the region in prior or subsequent periods.

point bar

A low ridge of sediment that forms along the inner bank of a meandering stream.

polymorph

A mineral that is identical to another mineral in chemical composition but differs from it in crystal structure.

porosity

The percentage of a soil, rock, or sediment's volume that is made up of pores.

porphyry copper deposit

A crystallized rock, typically porphyritic, having hairline fractures that contain copper and other metals.

potassium-argon dating

A form of isotope dating that relies on the extremely long half-life of radioactive isotopes of potassium, which decay into isotopes of argon, to determine the age of rocks in which argon is present. Potassium-argon dating is used for rocks between 100,000 and 4 billion years old.

potentia

The combined influence of gravity and water pressure on groundwater flow at a given depth.

potentiometric surface

The level to which the water in an artesian aquifer would rise if unaffected by friction with the surrounding rocks and sediments.

primary coast

A coast shaped primarily by nonmarine processes, such as glacial erosion or biological processes.

principle of cross-cutting relationships

The scientific law stating that a pluton is always younger than the rock that surrounds it.

principle of faunal succession

The scientific law stating that specific groups of animals have followed, or succeeded, one another in a definite sequence through Earth history.

principle of original horizontality

The scientific law stating that sediments settling out from bodies of water are deposited horizontally or nearly horizontally in layers that lie parallel or nearly parallel to the Earth's surface.

principle of superposition

The scientific law stating that in any unaltered sequence of rock strata, each stratum is younger than the one beneath it and older than the one above it, so that the youngest stratum will be at the top of the sequence and the oldest at the bottom.

principle of uniformitarianism

The scientific law stating that the geological processes taking place in the present operated similarly in the past and can therefore be used to explain past geologic events.

property

A characteristic that distinguishes one substance from another.

proton

A positively charged particle that is found in the nucleus of an atom and has a mass approximately 1836 times that of an electron.

P wave(abbreviation for primary wave)

A body wave that causes the compression of rocks when its energy acts upon them. When the P wave moves past a rock, the rock expands beyond its original volume, only to be compressed again by the next P wave. P waves are the fastest of all seismic waves. See also S wave.

P-wave shadow zone

The region that extends from 103º to 143º from the epicenter of an earthquake and is marked by the absence of P waves. The P-wave shadow zone is due to the refraction of seismic waves in the liquid outer core. See also S-wave shadow zone.

pyroclastic

Being or pertaining to rock fragments formed in a volcanic eruption.

pyroclastic cone

A usually steep, conic volcano composed almost entirely of an accumulation of loose pyroclastic material. Pyro-clastic cones are usually less than 450 meters high. Because no lava binds the pyroclastics, pyroclastic cones erode easily.

pyroclastic eruption

A volcanic eruption of viscous, gas-rich magma. Pyroclastic eruptions tend to produce a great deal of solid volcanic fragments rather than fluid lava.

pyroclastic flow

A rapid, extremely hot, downward stream of pyroclastics, air, gases, and ash ejected from an erupting volcano. A pyroclastic flow may be as hot as 800ºC or more and may move at speeds exceeding 150 kilometers per hour.

pyroclastics

(used only in the plural) Particles and chunks of igneous rock ejected from a volcanic vent during an eruption.

Glossary - Geology (N-O)

2008-03-23T05:05:00.001-07:00

natural bridge

An arch-shaped stretch of bedrock remaining in a karst region when the surrounding bedrock has dissolved.

natural spring

A place where groundwater flows to the surface and issues freely from the ground.

neutron

A particle that is found in the nucleus of an atom, has a mass approximately equal to that of a proton, and has no electric charge.

normal fault

A dip-slip fault marked by a generally steep dip along which the hanging wall has moved downward relative to the footwall.

nuclear fission

The division of the nuclei of isotopes of certain heavy elements, such as uranium and plutonium, effected by bombardment with neutrons. Nuclear fission causes the release of energy, additional neutrons, and an enormous quantity of heat. Nuclear fission is used in nuclear power plants and nuclear weapons. A by product of nuclear fission is toxic radioactive waste. See also nuclear fusion.

nuclear fusion

The combination of the nuclei of certain extremely light elements, especially hydrogen, effected by the application of high temperature and pressure. Nuclear fusion causes the release of an enormous amount of heat energy, comparable to that released by nuclear fission. The principal by product of nuclear fusion is helium.

nucleus (plural nuclei)

The central part of an atom, containing most of the atom's mass and having a positive charge due to the presence of protons.

nuée ardente

A sometimes glowing cloud of gas and pyroclastics erupted from a volcano and moving swiftly down its slopes. Also called a pyroclastic flow.

numerical dating

The fixing of a geological structure or event in time, as by counting tree rings

oblique slip

Fault motion that involves both dip-slip and strike-slip movement of fault blocks.

ocean trench

A deep, linear, relatively narrow depression in the sea floor, formed by the subduction of oceanic plates.

octet

rule A scientific law stating that all atoms, except those of hydrogen and helium, require eight electrons in the outermost energy level to maintain chemical stability.

oil sand

A mixture of unconsolidated sand and clay that contains a semi-solid bitumen.

oil shale

A brown or black clastic source rock containing kerogen.

ophiolite suite

The group of sediments, sedimentary rocks, and mafic and ultramafic igneous rocks that make up the oceanic lithosphere.

ore

A mineral deposit that can be mined for a profit.

orogenesis

Mountain formation, as caused by volcanism, subduction, plate divergence, folding, or the movement of fault blocks. Also called orogeny.

oscillatory motion

The circular movement of water up and down, with little or no change in position, as a wave passes.

outwash

A load of sediment, consisting of sand and gravel, that is deposited by meltwater in front of a glacier.

oxbow lake

A crescent-shaped body of standing water formed from a single loop that was cut off from a meandering stream, typically by a flood that allowed the stream to flow through its floodplain and bypass the loop.

oxidation

The process of combining with oxygen ions. A mineral that is exposed to air may undergo oxidation as a form of chemical weathering.

oxide

One of several minerals containing negative oxygen ions bonded to one or more positive metallic ions.

Glossary - Geology (M)

2008-03-23T05:04:00.001-07:00

magma

Molten (melted) rock that forms naturally within the Earth. Magma may be either a liquid or a fluid mixture of liquid, crystals, and dissolved gases.

magnetic field

The region within which the magnetism of a given substance or particle affects other substances.

magnetic reversal

The process by which the Earth's magnetic north pole and its magnetic south pole reverse their positions over time.

magnetism

The property, possessed by certain materials, to attract or repel similar materials. Magnetism is associated with moving electricity.

mantle

The middle layer of the Earth, lying just below the crust and consisting of relatively dense rocks. The mantle is divided into two sections, the upper mantle and the lower mantle; the lower mantle has greater density than the upper mantle. See also core and crust.

marble

A coarse-grained, nonfoliated metamorphic rock derived from limestone or dolostone.

marine magnetic anomaly

An irregularity in magnetic strength along the ocean floor that reflects sea-floor spreading during periods of magnetic reversal.

massive sulfide deposit

An unusually large deposit of sulfide minerals.

meandering stream

A stream that traverses relatively flat land in fairly evenly spaced loops and separated from each other by narrow strips of floodplain.

mechanical exfoliation

A form of mechanical weathering in which successive layers of a large plutonic rock break loose and fall when the erosion of overlying material permits the rock to expand upward. The thin slabs of rock that break off fall parallel to the exposed surface of the rock, creating the long, broad steps that can be found on many mountains.

mechanical weathering

The process by which a rock or mineral is broken down into smaller fragments without altering its chemical makeup; weathering that affects only physical characteristics. See also chemical weathering.

mélange

A body of rock that forms along the inner wall of an ocean trench and is made up of fragments of lithosphere and oceanic sediment that have undergone metamorphism.

mercalli intensity scale

A scale designed to measure the degree of intensity of earthquakes, ranging from I for the lowest intensity to XII for the highest. The classifications are based on human perceptions.

mesozoic era

The intermediate era of the Phanerozoic Eon, following the Paleozoic Era and preceding the Cenozoic Era, and marked by the dominance of marine and terrestrial reptiles, and the appearance of birds, mammals, and flowering plants.

metallic bonding

The act or process by which two or more atoms of electron-donating elements pack so closely together that some of their electrons begin to wander among the nuclei rather than orbiting the nucleus of a single atom. Metallic bonding is responsible for the distinctive properties of metals.

metamorphic differentiation

The process by which minerals from a chemically uniform rock separate from each other during metamorphism and form individual layers within a new metamorphic rock.

metamorphic grade

A measure used to identify the degree to which a metamorphic rock has changed from its parent rock. A metamorphic grade provides some indication of the circumstances under which the metamorphism took place.

metamorphic index mineral

One of a set of minerals found in metamorphic rocks and used as indicators of the temperature and pressure conditions at which the metamorphism occurred. A metamorphic index mineral is stable only within a narrow range of temperatures and pressures, and the metamorphism that produces it must take place within that range.

metamorphic rock

A rock that has undergone chemical or structural changes. Heat, pressure, or a chemical reaction may cause such changes.

metamorphism

The process by which conditions within the Earth, below the zone of diagenesis, alter the mineral content, chemical composition, and structure of solid rock without melting it. Igneous, sedimentary, and metamorphic rocks may all undergo metamorphism.

meteoric water

The precipitation of condensed water from clouds as rain, snow, sleet, or hail.

microcontinent

A section of continental lithosphere that has broken off from a larger, distant continent, as by rifting.

migmatite

A rock that incorporates both metamorphic and igneous materials.

mineral

A naturally occurring, usually inorganic, solid consisting of either a single element or a compound, and having a definite chemical composition and a systematic internal arrangement of atoms.

mineraloid

A naturally occurring, usually inorganic, solid consisting of either a single element or a compound, and having a definite chemical composition but lacking a systemic internal arrangement of atoms. See also mineral.

Moho (abbreviation for Mohorovi?cic´)

The seismic discontinuity between the base of the Earth's crust and the top of the mantle. P waves passing through the Moho change their velocity by approximately one kilometer per second, with the higher velocity occurring in the mantle and the lower in the crust.

moment-magnitude scale

A recently developed alternative to the Richter scale used to measure more accurately the amount of energy released by large earthquakes. This scale involves measurement of an earthquake's seismic moment.

moraine

A single, large mass of glacial till that accumulates, typically at the edge of a glacier.

mudcrack

A fracture that develops at the top of a layer of fine grained, muddy sediment when it is exposed to the air, dries out, and then shrinks.

mudstone

A detrital sedimentary rock composed of clay-sized particles.

Glossary - Geology (J-L)

2008-03-23T05:01:00.000-07:00

jetty

A structure built along the bank of a stream channel or tidal outlet to direct the flow of a stream or tide and keep the sediment moving so that it cannot build up and fill the channel. Jetties are typically built in parallel pairs along both banks of the channel. Jetties that are built perpendicular to a coast tend to interrupt longshore drift and thus widen beaches.

joint

A fracture dividing a rock into two sections that have not visibly moved relative to each other. See also fault.

juvenile water

The steam that accompanies volcanic eruptions.

karst

A topography characterized by caves, sinkholes, disappearing streams, and underground drainage. Karst forms when groundwater dissolves pockets of limestone, dolomite, or gypsum in bedrock.

kerogen

A solid, waxy, organic substance that forms when pressure and heat from the Earth act on the remains of plants and animals. Kerogen converts to various liquid and gaseous hydrocarbons at a depth of 7 or more kilometers and a temperature between 50º and 100ºC.

laccolith

A large concordant pluton that is shaped like a dome or a mushroom. Laccoliths tend to form at relatively shallow depths and are typically composed of granite. The country rock above them often erodes away completely.

lahar

A flow of pyroclastic material mixed with water. A lahar is often produced when a snow-capped volcano erupts and hot pyroclastics melt a large amount of snow or ice.

lava

Magma that comes to the Earth's surface through a volcano or fissure.

leach

To dissolve from a rock. For example, when acidic water passes through fractured rocks, soluble minerals leach, or dissolve, from the rocks.

levee

A protective barrier built along the banks of a stream to prevent flooding. See also natural levee.

lichen

Plant-like colonies of fungi and algae that grow on the exposed surface of rocks. Lichen grow at a constant rate within a single geographic area.

lichenometry

A method of numerical dating that uses the size of lichen colonies on a rock surface to determine the surface's age. Lich-enometry is used for rock surfaces less than about 9000 years old.

lignite

A soft, brownish coal that develops from peat through bacterial action, is rich in kerogen, and has a carbon content of 70%, which makes it a more efficient heating fuel than peat.

limestone

A sedimentary rock composed primarily of calcium carbonate. Some 10% to 15% of all sedimentary rocks are limestones. Limestone is usually organic, but it may also be inorganic.

liquefaction

The conversion of moderately cohesive, unconsolidated sediment into a fluid, water-saturated mass.

lithification

The conversion of loose sediment into solid sedimentary rock.

lithosphere

A layer of solid, brittle rock making up the outer 100 kilometers of the Earth, encompassing both the crust and the outermost part of the upper mantle. See also asthenosphere.

lithostatic pressure

The force exerted on a rock buried deep within the Earth by overlying rocks. Because lithostatic pressure is exerted equally from all sides of a rock, it compresses the rock into a smaller, denser form without altering the rock's shape.

loess

A load of silt that is produced by the erosion of outwash and transported by wind. Much loess found in the Mississippi Valley, China, and Europe is believed to have been deposited during the Pleistocene Epoch.

longitudinal dune

One of a series of long, narrow dunes lying parallel both to each other and to the prevailing wind direction. Longi-tudinal dunes range from 60 meters to 100 kilometers in length and from 3 to 50 meters in height.

longshore current

An ocean current that flows close and almost parallel to the shoreline and is caused by the rush of waves toward the shore.

longshore drift

1. The process by which a current moves sediments along a surf zone. 2. The sediments so moved. Longshore drift typically consists of sand, gravel, shell fragments, and pebbles. See also beach drift.

lopolith

A saucer-shaped intrusive body of igneous rock. Lopoliths are typically mafic in composition.

low-velocity zone

An area within the Earth's upper mantle in which both P waves and S waves travel at markedly slower velocities than in the outermost part of the upper mantle. The low-velocity zone occurs in the range between 100 and 350 kilometers of depth.

luster

1. The reflection of light on a given mineral's surface, classified by intensity and quality. 2. The appearance of a given mineral as characterized by the intensity and quality with which it reflects light.

Glossary - Geology (I)

2008-03-23T05:00:00.000-07:00

ice age

A period during which the Earth is substantially cooler than usual and a significant portion of its land surface is covered by glaciers. Ice ages generally last tens of millions of years.

ice cap

An alpine glacier that covers the peak of a mountain.

igneous rock

A rock made from molten (melted) or partly molten material that has cooled and solidified.

index fossil

The fossil of an organism known to have existed for a relatively short period of time, used to date the rock in which it is found.

inorganic chemical sediment

Sedimentary rocks - such as limestone, chert, and evaporites - that forms when the dissolved products of chemical weathering precipitate from solution. The ornate columns of travertine in caves is one example of an inorganic chemical sedimentar rock.

inselberg

A steep ridge or hill left when a mountain has eroded and found in an otherwise flat, typically desert plain.

intermolecular bonding

The act or process by which two or more groups of atoms or molecules combine due to weak positive or negative charges that develop at various points within each group of atoms due to uneven distribution of their electrons. The side of the molecule where electrons are more likely to be found will have a slight negative charge, and the side where they are less likely to be found will have a slight positive charge. Such charged regions attract oppositely charged regions of nearby molecules, forming relatively weak bonds.

internal deformation

The rearrangement of the planes within ice crystals, due to pressure from overlying ice and snow, that causes the downward or outward flow of a glacier.

intrusive rock

An igneous rock formed by the entrance of magma into preexisting rock.

ion

An atom that has lost or gained one or more electrons, thereby becoming electrically charged.

ionic bond

The combination of an atom that has a strong tendency to lose electrons with an atom that has a strong tendency to gain electrons, such that the former transfers one or more electrons to the latter and each achieves chemical stability under the octet rule. The atom that loses electrons acquires a positive electric charge and the atom that gains electrons acquires a negative electric charge, so that the resulting compound is electrically neutral.

ionic bonding

The act or process of forming of an ionic bond.

ionic substitution

The replacement of one type of ion in a mineral by another that is similar to the first in size and charge.

isostasy

The equilibrium maintained between the gravity tending to depress and the buoyancy tending to raise a given segment of the lithosphere as it floats above the asthenosphere.

isotope

One of two or more forms of a single element; the atoms of each isotope have the same number of protons but different numbers of neutrons in their nuclei. Thus isotopes have the same atomic number but differ in atomic mass.

isotope dating

The process of using relative proportions of parent to daughter isotopes in radioactive decay to determine the age of a given rock or rock stratum.

Glossary - Geology (H)

2008-03-23T04:59:00.000-07:00

half-life

The time necessary for half of the atoms of a parent isotope to decay into the daughter isotope.

hardness

The degree of resistance of a given mineral to scratching, indicating the strength of the bonds that hold the mineral's atoms together. The hardness of a mineral is measured by rubbing it with substances of known hardness.

headland

A cliff that projects out from a coast into deep water.

holocene Epoch

The second epoch of the Quaternary Period, beginning approximately 10,000 years ago and continuing to the pres-ent time. See also Pleistocene Epoch.

hook

A spit that curves sharply at its coastal end.

horn

A high mountain peak that forms when the walls of three or more cirques intersect.

hornfels

A hard, dark-colored, dense metamorphic rock that forms from the intrusion of magma into shale or basalt.

horst

A block of rock that lies between two faults and has moved upward relative to the two adjacent fault blocks. See also graben.

hot spot

An area in the upper mantle, ranging from 100 to 200 kilometers in width, from which magma rises in a plume to form volcanoes. A hot spot may endure for 10 million years or more.

hydraulic conductivity

The extent to which a given substance allows water to flow through it, determined by such factors as sorting and grain size and shape.

hydraulic gradient

The difference in potential between two points, divided by the lateral distance between the points.

hydraulic lifting

The erosion of a stream bed by water pressure.

hydrocarbon

A molecule that is entirely made up of hydrogen and carbon.

hydrogen bond

An intermolecular bond formed with hydrogen.

hydrologic cycle

The perpetual movement of water among the mantle, oceans, land, and atmosphere of the Earth.

hydrolysis

A form of chemical weathering in which ions from water replace equivalently charged ions from a mineral, especially a silicate.

hydrothermal deposit

A mineral deposit formed by the precipitation of metallic ions from water ranging in temperature from 50º to 700ºC.

hypothesis

A tentative explanation of a given set of data that is expected to remain valid after future observation and experimentation. See also theory.

Glossary - Geology (G)

2008-03-23T04:58:00.000-07:00

gabbro

Any of a group of dark, dense, phaneritic, intrusive rocks that are the plutonic equivalent to basalt.

geochronology

The study of the relationship between the history of the Earth and time.

geologic time scale

The division of all of Earth history into blocks of time distinguished by geologic and evolutionary events, ordered sequentially and arranged into eons made up of eras, which are in turn made up of periods, which are in turn made up of epochs.

geology

The scientific study of the Earth, its origins and evolution, the materials that make it up, and the processes that act on it.

geophysics

The branch of geology that studies the physics of the Earth, using the physical principles underlying such phenomena as seismic waves, heat flow, gravity, and magnetism to investigate planetary properties.

geyser

A natural spring marked by the intermittent escape of hot water and steam.

glacial abrasion

The process by which a glacier erodes the underlying bedrock through contact between the bedrock and rock fragments embedded in the base of the glacier. See also glacial quarrying.

glacial drift

A load of rock material transported and deposited by a glacier. Glacial drift is usually deposited when the glacier begins to melt.

glacial erratic

A rock or rock fragment transported by a glacier and deposited on bedrock of different composition. Glacial erratics range from a few millimeters to several yards in diameter.

glacial quarrying

The process by which a glacier erodes the underlying bedrock by loosening and ultimately detaching blocks of rock from the bedrock and attaching them instead to the glacier, which then bears the rock fragments away. See also glacial abrasion.

glacial till

Drift that is deposited directly from glacial ice and therefore not sorted. Also called till. See also glacial drift.

glacier

A moving body of ice that forms on land from the accumulation and compaction of snow, and that flows downslope or outward due to gravity and the pressure of its own weight.

gneiss

A coarse-grained, foliated metamorphic rock marked by bands of light-colored minerals such as quartz and feldspar that alternate with bands of dark-colored minerals. This alternation develops through metamorphic differentiation.

graben

A block of rock that lies between two faults and has moved downward to form a depression between the two adjacent fault blocks. See also horst.

graded bed

A bed formed by the deposition of sediment in relatively still water, marked by the presence of particles that vary in size, density, and shape. The particles settle in a gradual slope with the coarsest particles at the bottom and the finest at the top.

graded stream

A stream maintaining an equilibrium between the processes of erosion and deposition, and therefore between aggradation and degradation.

gradient

The vertical drop in a stream's elevation over a given horizontal distance, expressed as an angle.

granite

A pink-colored, felsic, plutonic rock that contains potassium and usually sodium feldspars, and has a quartz content of about 10%. Granite is commonly found on continents but virtually absent from the ocean basins.

gravity

1. The force of attraction exerted by one body in the universe on another. Gravity is directly proportional to the product of the masses of the two attracted bodies. 2. The force of attraction exerted by the Earth on bodies on or near its surface, tending to pull them toward the Earth's center.

gravity anomaly

The difference between an actual measurement of gravity at a given location and the measurement predicted by theoretical calculation.

groin

A structure that juts out into a body of water perpendicular to the shoreline and is built to restore an eroding beach by intercepting longshore drift and trapping sand.

guyot

A seamount, the top of which has been flattened by weathering, wave action, or stream erosion.

Glossary - Geology (F)

2008-03-23T04:57:00.000-07:00

fall

The fastest form of mass movement, occurring when rock or sediment breaks off from a steep or vertical slope and descends at a rate of 9.8 meters per second. A fall can be extremely dangerous.

fault

A fracture dividing a rock into two sections that have visibly moved relative to each other.

fault block

A section of rock separated from other rock by one or more faults.

fault-block mountain

A mountain containing tall horsts interspersed with much lower grabens and bounded on at least one side by a high-angle normal fault.

fault-zone metamorphism

The metamorphism that acts on rocks grinding past one another along a fault and is caused by directed pressure and frictional heat.

firn

Firmly packed snow that has survived a summer melting season. Firn has a density of about 0.4 gram per cubic centimeter. Ultimately, firn turns into glacial ice.

fission tracks

Marks left in the latticework of a mineral crystal by subatomic particles released during the fission of a radioactive atom trapped inside the crystal.

fjord

A deep, steep-walled, U-shaped valley formed by erosion by a glacier and submerged with seawater.

floodplain

The flat land that surrounds a stream and becomes submerged when the stream overflows its banks.

flood tide

A tide that raises the water surface of an ocean and moves the shoreline farther inland.

flow

A relatively rapid mass-movement process that involves a mixture of rock, soil, vegetation, and water moving downslope as a viscous fluid. Within a flow (such as a mudflow), each particle, regardless of its size, moves independently.

fluorescence

Emission of visible light by a substance, such as a mineral, that is currently exposed to ultraviolet light and absorbs radiation from it. The light appears in the form of glowing, distinctive colors. The emission ends when the exposure to ultraviolet light ends.

focus (plural foci)

The precise point within the Earth's crust or mantle where rocks begin to rupture or move in an earthquake.

fold

A bend that develops in an initially horizontal layer of rock, usually caused by plastic deformation. Folds occur most frequently in sedimentary rocks.

foliation

The arrangement of a set of minerals in parallel, sheet-like layers that lie perpendicular to the flattened plane of a rock. Occurs in metamorphic rocks on which directed pressure has been exerted.

forearc basin

A depression in the sea floor located between an accretionary wedge and a volcanic arc in a subduction zone, and lined with trapped sediment. See also backarc basin.

foreshock

A minor, barely detectable earthquake, generally preceding a full-scale earthquake with approximately the same focus. Major quakes may follow a cluster of foreshocks by as little as a few seconds or as much as several weeks.

foreshore

The portion of a beach that lies nearest to the sea, extending from the low-tide line to the high-tide line.

fossil fuel

A nonrenewable energy source, such as oil, gas, or coal, that derives from the organic remains of past life. Fossil fuels consist primarily of hydrocarbons.

fractional crystallization

The process by which a magma produces crystals that then separate from the original magma, so that the chemical composition of the magma changes with each generation of crystals, producing igneous rocks of different compositions. The silica content of the magma becomes proportionately higher after each crystallization.

fracture

(n) A crack or break in a rock. (v) To break in random places instead of cleaving. Said of minerals.

fringing reef

A reef that forms against or near an island or continental coast and grows seaward, sloping sharply toward the sea floor. Fringing reefs usually range from 0.5 to 1.0 or more kilometers in width.

frost wedging

A form of mechanical weathering caused by the freezing of water that has entered a pore or crack in a rock. The water expands as it freezes, widening the cracks or pores and often loosening or dislodging rock fragments. As the ice forms, it attracts more water, increasing the effects of frost wedging.

Glossary - Geology (E)

2008-03-23T04:56:00.000-07:00

earthquake

A movement within the Earth's crust or mantle, caused by the sudden rupture or repositioning of underground rocks as they release stress.

earth systems

The Earth is made up of four basic systems: the lithosphere (the rocks of the earth); the hydrosphere (the waters of the Earth); the atmosphere (the gases that surround the Earth); and, the biosphere (the life on Earth). These systems interact to produce most of the geological processes that occur on Earth. An event involving one of these systems may affect some or all of the others.

ebb tide

A tide that lowers the water surface of an ocean and moves the shoreline farther seaward.

echo-sounding sonar

The mapping of ocean topography based on the time required for sound waves to reach the sea floor and return to the research ship that emits them.

elastic deformation

A temporary stress-induced change in the shape or volume of a rock, after which the rock returns to its original shape and volume.

elastic limit

See yield point.

electron

A negatively charged particle that orbits rapidly around the nucleus of an atom. See also proton.

element

A form of matter that cannot be broken down into a chemically simpler form by heating, cooling, or chemical reactions. There are 115 known elements, 92 of them natural and 23 man-made. Elements are represented by one- or two-letter abbreviations. See also atom, atomic number.

energy level

The path of a given electron's orbit around a nucleus, marked by a constant distance from the nucleus.

epicenter

The point on the Earth's surface that is located directly above the focus of an earthquake.

equilibrium line

The point in a glacier where overall gain in volume equals overall loss, so that the net volume remains stable. The equilibrium line marks the border between the zone of accumulation and the zone of ablation.

erosion

The process by which particles of rock and soil are loosened, as by weathering, and then transported elsewhere, as by wind, water, ice, or gravity.

esker

A ridge of sediment that forms under a glacier's zone of ablation, made up of sand and gravel deposited by meltwater. An esker may be less than 100 meters or more than 500 kilometers long, and may be anywhere from 3 to over 300 meters high.

evaporite

An inorganic chemical sediment that precipitates when the salty water in which it had dissolved evaporates.

extrusive rock

An igneous rock formed from lava that has flowed out onto the Earth's surface, characterized by rapid solidification and grains that are so small as to be barely visible to the naked eye.

Glossary - Geology (D)

2008-03-23T04:54:00.000-07:00

daughter isotope

An isotope that forms from the radioactive decay of a parent isotope. A daughter isotope may or may not be of the same element as its parent. If the daughter isotope is radioactive, it will eventually become the parent isotope of a new daughter isotope. The last daughter isotope to form from this process will be stable and nonradioactive.

debris flow

1. The rapid, downward mass movement of particles coarser than sand, often including boulders one meter or more in diameter, at a rate ranging from 2 to 40 kilometers per hour. Debris flows occur along fairly steep slopes. 2. The material that descends in such a flow. deflation The process by which wind erodes bedrock by picking up and transporting loose rock particles.

degradation

The process by which a stream's gradient becomes less steep, due to the erosion of sediment from the stream bed. Such erosion generally follows a sharp reduction in the amount of sediment entering the stream.

delta

An alluvial fan having its apex at the mouth of a stream.

dendrochronology

A method of numerical dating that uses the number of tree rings found in a cross section of a tree trunk or branch to determine the age of the tree.

desert

A region with an average annual rainfall of 10 inches or less and sparse vegetation, typically having thin, dry, and crumbly soil. A desert has an aridity index greater than 4.0.

desertification

The process through which a desert takes over a formerly non-desert area. When a region begins to undergo desertification, the new conditions typically include a significantly lowered water table, a reduced supply of surface water, increased salinity in natural waters and soils, progressive destruction of native vegetation, and an accelerated rate of erosion.

desert pavement

A closely packed layer of rock fragments concentrated in a layer along the Earth's surface by the deflation of finer particles.

desert varnish

A thin, shiny red-brown or black layer, principally composed of iron manganese oxides, that coats the surfaces of many exposed desert rocks.

detrital sediment

Sediment that is composed of transported solid fragments of preexisting igneous, sedimentary, or metamorphic rocks.

diagenesis

The set of processes that cause physical and chemical changes in sediment after it has been deposited and buried under another layer of sediment. Diagenesis may culminate in lithification.

dike

A discordant pluton that is substantially wider than it is thick. Dikes are often steeply inclined or nearly vertical. See also sill. dilatancy The expansion of a rock's volume caused by stress and deformation.

diorite

Any of a group of dark, phaneritic, intrusive rocks that are the plutonic equivalents of andesite.

dip

The angle formed by the inclined plane of a geological structure and the horizontal plane of the Earth's surface.

dip-slip fault

A fault in which two sections of rock have moved apart vertically, parallel to the dip of the fault plane.

directed pressure

Force exerted on a rock along one plane, flattening the rock in that plane and lengthening it in the perpendicular plane.

disappearing stream

A surface stream that drains rapidly and completely into a sinkhole.

displaced terrane

A fault-bounded body of rock - sometimes thousands of square kilometers in area - that originated elsewhere geographically and has then moved, perhaps long distances, by plate motion.

dissolution

A form of chemical weathering in which water molecules, sometimes in combination with acid or another compound in the environment, attract and remove oppositely charged ions or ion groups from a mineral or rock.

dissolved load

A body of sediment carried by a stream in the form of ions that have dissolved in the water.

distributary

One of a network of small streams carrying water and sediment from a trunk stream into an ocean.

divergence

The process by which two lithospheric plates separated by rifting move farther apart, with soft mantle rock rising between them and forming new oceanic lithosphere. See also convergence.

dolostone

A sedimentary rock composed primarily of dolomite, a mineral made up of calcium, magnesium, carbon, and oxygen. Dolostone is thought to form when magnesium ions replace some of the calcium ions in limestone, to which dolostone is similar in both appearance and chemical structure.

dome

A round or oval bulge on the Earth's surface, containing the oldest section of rock in its raised, central part. See also basin. drainage basin The area from which water flows into a stream. Also called a watershed.

drainage divide

An area of raised, dry land separating two adjacent drainage basins.

drainage pattern

The arrangement in which a stream erodes the channels of its network of tributaries.

drumlin

A long, spoon-shaped hill that develops when pressure from an overriding glacier reshapes a moraine. Drumlins range in height from 5 to 50 meters and in length from 400 to 2000 meters. They slope down in the direction of the ice flow.

dune

A usually asymmetrical mound or ridge of sand that has been transported and deposited by wind. Dunes form in both arid and humid climates.

dynamothermal metamorphism

A form of regional metamorphism that acts on rocks caught between two converging plates and is initially caused by directed pressure from the plates, which causes some of the rocks to rise and others to sink, sometimes by tens of kilometers. The rocks that fall then experience further dynamothermal metamorphism, this time caused by heat from the Earth's interior and lithostatic pressure from overlying rocks.

Glossary - Geology (C)

2008-03-23T04:52:00.000-07:00

caldera

A vast depression at the top of a volcanic cone, formed when an eruption substantially empties the reservoir of magma beneath the cone's summit. Eventually the summit collapses inward, creating a caldera. A caldera may be more than 15 kilometers in diameter and more than 1000 meters deep.

caliche

A white soil horizon consisting of calcium carbonate, typical of arid and semi-arid areas. Brief heavy rains dissolve calcium carbonate in the upper layers of soil and transport it downward; the rainwater then evaporates rapidly, leaving the calcium carbonate to form a new, solid layer of soil.

capacity

The ability of a given stream to carry sediment, measured as the maximum quantity it can transport past a given point on the channel bank in a given amount of time. See also competence.

capillary fringe

The lowest part of the zone of aeration, marked by the rising of water from the water table due to the attraction of the water molecules to mineral surfaces and other molecules, and to pressure from the zone of saturation below.

carbon-14 dating

A form of isotope dating that relies on the 5730-year half-life of radioactive carbon-14, which decays into nitrogen-14, to determine the age of rocks in which carbon-14 is present. Carbon-14 dating is used for rocks from 100 to 100,000 years old.

carbonate

One of several minerals containing one central carbon atom with strong covalent bonds to three oxygen atoms and typically having ionic bonds to one or more positive ions.

catastrophism

The hypothesis that a series of immense, brief, worldwide upheavals changed the Earth's crust greatly and can account for the development of mountains, valleys, and other features of the Earth. See also uniformitarianism.

cave

A naturally formed opening beneath the surface of the Earth, generally formed by dissolution of carbonate bedrock. Caves may also form by erosion of coastal bedrock, partial melting of glaciers, or solidification of lava into hollow tubes.

cementation

The diagenetic process by which sediment grains are bound together by precipitated minerals originally dissolved during the chemical weathering of preexisting rocks.

Cenozoic Era

The latest era of the Phanerozoic Eon, following the Mesozoic Era and continuing to the present time, and marked by the presence of a wide variety of mammals, including the first hominids.

chemical sediment

Sediment that is composed of previously dissolved minerals that have either precipitated from evaporated water or been extracted from water by living organisms and deposited when the organisms died or discarded their shells.

chemical weathering

The process by which chemical reactions alter the chemical composition of rocks and minerals that are unstable at the Earth's surface and convert them into more stable substances; weathering that changes the chemical makeup of a rock or mineral. See also mechanical weathering.

chert

A member of a group of sedimentary rocks that consist primarily of microscopic silica crystals. Chert may be either organic or inorganic, but the most common forms are inorganic.

chondrules

Small nuggets of rocky material that exist in certain meteorites. These droplets of matter are believed to have condensed from our solar system's original nebula about five billion years ago. Their primary element is iron.

cinder cone

A pyroclastic cone composed primarily of cinders.

cirque

A deep, semi-circular basin eroded out of a mountain by an alpine glacier.

cirque glacier

A small alpine glacier that forms inside a cirque, typ-ically near the head of a valley.

clastic

Being or pertaining to a sedimentary rock composed primarily from fragments of preexisting rocks or fossils.

cleavage

The tendency of certain minerals to break along distinct planes in their crystal structures where the bonds are weakest. Cleavage is tested by striking or hammering a mineral, and is classified by the number of surfaces it produces and the angles between adjacent surfaces.

coal

A member of a group of easily combustible, organic sedimentary rocks composed mostly of plant remains and containing a high proportion of carbon.

coast

The area of dry land that borders on a body of water.

col

A high mountain pass that forms when part of an arête erodes.

compaction

The diagenetic process by which the volume or thickness of sediment is reduced due to pressure from overlying layers of sediment.

competence

The ability of a given stream to carry sediment, measured as the diameter of the largest particle that the stream can transport. See also capacity.

composite cone

See stratovolcano.

compound

An electrically neutral substance that consists of two or more elements combined in specific, constant proportions. A compound typically has physical characteristics different from those of its constituent elements.

compression

Stress that reduces the volume or length of a rock, as that produced by the convergence of plate margins.

cone ofdepression

An area in a water table along which water has descended into a well to replace water drawn out, leaving a gap shaped like an inverted cone.

conglomerate

A clastic rock composed of particles more than 2 millimeters in diameter and marked by the roundness of its component grains and rock fragments.

contact metamorphism

Metamorphism that is caused by heat from a magmatic intrusion.

continental collision

The convergence of two continental plates, resulting in the formation of mountain ranges.

continental drift

The hypothesis, proposed by Alfred Wegener, that today's continents broke off from a single supercontinent and then plowed through the ocean floors into their present positions. This explanation of the shapes and locations of Earth's current continents evolved into the theory of plate tectonics.

continental ice sheet

An unconfined glacier that covers much or all of a continent.

continental platform

Continental platforms are the regions adjacent to and surrounding the continental shields. They are typically a relatively thin veneer of sedimentary rock that buries the edges of the shields.

continental shield

Broad areas of exposed ancient crystalline rocks in the cores of the Earth's continents. These rocks are typically the oldest on the continentes, many more than 2.5 billion years old.

convection cell

The cycle of movement in the asthenosphere that causes the plates of the lithosphere to move. Heated material in the asthenosphere becomes less dense and rises toward the solid lithosphere, through which it cannot rise further. It therefore begins to move horizontally, dragging the lithosphere along with it and pushing forward the cooler, denser material in its path. The cooler material eventually sinks down lower into the mantle, becoming heated there and rising up again, continuing the cycle. See also plate tectonics.

convergence

The coming together of two lithospheric plates. Con-vergence causes subduction when one or both plates is oceanic, and mountain formation when both plates are continental. See also divergence.

core

The innermost layer of the Earth, consisting primarily of pure metals such as iron and nickel. The core is the densest layer of the Earth, and is divided into the outer core, which is believed to be liquid, and the inner core, which is believed to be solid. See also crust and mantle.

correlation

The process of determining that two or more geographically distant rocks or rock strata originated in the same time period.

covalent bond

The combination of two or more atoms by sharing electrons so as to achieve chemical stability under the octet rule. Atoms that form covalent bonds generally have outer energy levels containing three, four, or five electrons. Covalent bonds are generally stronger than other bonds.

craton

The segment of the Earth's continents that have remained tectonically stable and relatively earthquake-free for a vast period of time. The craton is composed of the continental shield and the surrounding continental platform.

creep

The slowest form of mass movement, measured in millimeters or centimeters per year and occurring on virtually all slopes. cross bed A bed made up of particles dropped from a moving current, as of wind or water, and marked by a downward slope that indicates the direction of the current that deposited them.

crust

The outermost layer of the Earth, consisting of relatively low-density rocks. See also core and mantle.

crystal

A mineral in which the systematic internal arrangement of atoms is outwardly reflected as a latticework of repeated three-dimensional units that form a geometric solid with a surface consisting of symmetrical planes.

crystal structure

1. The geometric pattern created by the systematic internal arrangement of atoms in a mineral. 2. The systematic internal arrangement of atoms in a mineral. See also crystal.

Glossary - Geology (B)

2008-03-23T04:49:00.000-07:00

backarc basin

A depression landward of a volcanic arc in a subduction zone, which is lined with trapped sediment from the volcanic arc and the plate interior. See also forearc basin.

backarc spreading

The process by which the overriding plate in a subduction zone becomes stretched to the point of rifting, so that magma can then rise into the gap created by the rift. Backarc spreading typically occurs when the subducting plate sinks more rapidly than the overriding plate moves forward.

backshore

The portion of a beach that extends from the high-tide line inland to the sea cliff or vegetation line. Swash reaches the backshore only during major storms.

backswamp

The section of a floodplain where deposits of fine silts and clays settle after a flood. Backswamps usually lie behind a stream's natural levees.

banded iron formation

A rock that is made up of alternating light silica-rich layers and dark-colored layers of iron-rich minerals, which were deposited in marine basins on every continent about 2 billion years ago.

barchan dune

A crescent-shaped dune that forms around a small patch of vegetation, lies perpendicular to the prevailing wind direction, and has a gentle, convex windward slope and a steep, concave leeward slope. Barchan dunes typically form in arid, inland deserts with stable wind direction and relatively little sand.

barrier island

A ridge of sand that runs parallel to the main coast but is separated from it by a bay or lagoon. Barrier islands range from 10 to 100 kilometers in length and from 2 to 5 kilometers in width. A barrier island may be as high as 6 meters above sea level. barrier reef A long, narrow reef that runs parallel to the main coast but is separated from it by a wide lagoon.

basal sliding

The process by which a glacier undergoes thawing at its base, producing a film of water along which the glacier then flows. Basal sliding primarily affects glaciers in warm climates or mid-latitude mountain ranges.

basalt

The dark, dense, aphanitic, extrusive rock that has a silica content of 40% to 50% and makes up most of the ocean floor. Basalt is the most abundant volcanic rock in the Earth's crust.

base level

The lowest level to which a stream can erode the channel through which it flows, generally equal to the prevailing global sea level.

basin

A round or oval depression in the Earth's surface, containing the youngest section of rock in its lowest, central part.

batholith

A massive discordant pluton with a surface area greater than 100 square kilometers, typically having a depth of about 30 kilometers. Batholiths are generally found in elongated mountain ranges after the country rock above them has eroded.

baymouth bar

A narrow ridge of sand that stretches completely across the mouth of a bay. (Also called bay bar and bay barrier.)

beach

The part of a coast that is washed by waves or tides, which cover it with sediments of various sizes and composition, such as sand or pebbles.

beach drift

1. The process by which swash and backwash move sediments along a beach face. 2. The sediments so moved. Beach drift typically consists of sand, gravel, shell fragments, and pebbles. See also longshore drift.

beach face

The portion of a foreshore that lies nearest to the sea and regularly receives the swash of breaking waves. The beach face is the steepest part of the foreshore.

bedding

The division of sediment or sedimentary rock into parallel layers (beds) that can be distinguished from each other by such features as chemical composition and grain size.

bed load

A body of coarse particles that move along the bottom of a stream.

Benioff-Wadati zone

A region where the subduction of oceanic plates causes earthquakes, the foci of which are deeper the farther inland they are.

berm

A low, narrow layer or mound of sediment deposited on a backshore by storm waves.

biogenic chemical sediment

Sedimentary rocks derived from living organisms. Common examples include fossiliferous limestones and coal.

biomass fuel

A renewable fuel derived from a living organism or the by product of a living organism. Biomass fuels include wood, dung, methane gas, and grain alcohol.

bitumen

Any of a group of solid and semi-solid hydrocarbons that can be converted into liquid form by heating. Bitumens can be refined to produce such commercial products as gasoline, fuel oil, and asphalt.

bituminous coal

A shiny black coal that develops from deeply buried lignite through heat and pressure, and that has a carbon content of 80% to 93%, which makes it a more efficient heating fuel than lignite.

body wave

A type of seismic wave that transmits energy from an earthquake's focus through the Earth's interior in all directions. See also surface wave.

bond

To combine, by means of chemical reaction, with another atom to form a compound. When an atom bonds with another, it either loses, gains, or shares electrons with the other atom.

Bowen's reaction series

The sequence of igneous rocks formed from a mafic magma, assuming mineral crystals that have already formed continue to react with the liquid magma and so evolve into new minerals, thereby creating the next rock in the sequence.

braided stream

A network of converging and diverging streams separated from each other by narrow strips of sand and gravel.

breakwater

A wall built seaward of a coast to intercept incoming waves and so protect a harbor or shore. Breakwaters are typically built parallel to the coast.

breccia

A clastic rock composed of particles more than 2 millimeters in diameter and marked by the angularity of its component grains and rock fragments.

breeder reactor

A nuclear reactor that manufactures more fissionable isotopes than it consumes. Breeder reactors use the widely available, nonfissionable uranium isotope U-238, together with small amounts of fissionable U-235, to produce a fissionable isotope of plutonium, Pu-239.

brittle failure

Rupture of rock, a type of permanent strain caused by relatively low stress.

burial metamorphism

A form of regional metamorphism that acts on rocks covered by 5 to 10 kilometers of rock or sediment, caused by heat from the Earth's interior and lithostatic pressure.

Glossary - Geology (A)

2008-03-23T04:44:00.001-07:00

abrasion

A form of mechanical weathering that occurs when loose fragments or particles of rocks and minerals that are being transported, as by water or air, collide with each other or scrape the surfaces of stationary rocks.

accretionary

wedge A mass of sediment and oceanic lithosphere that is transferred from a subducting plate to the less dense, overriding plate with which it converges.

acid rain

Rain that contains such acidic compounds as sulfuric acid and nitric acid, which are produced by the combination of atmospheric water with oxides released when hydrocarbons are burned. Acid rain is widely considered responsible for damaging forests, crops, and human-made structures, and for killing aqua-tic life.

aftershock

A ground tremor caused by the repositioning of rocks after an earthquake. Aftershocks may continue to occur for as long as two years after the initial earthquake. The intensity of an earthquake's aftershocks decreases over time.

aggradation

The process by which a stream's gradient steepens due to increased deposition of sediment.

alloy

A metal that is manufactured by combining two or more molten metals. An alloy is always harder than its component metals. Bronze is an alloy of copper and tin.

alluvial fan

A triangular deposit of sediment left by a stream that has lost velocity upon entering a broad, relatively flat valley.

alluvium

A deposit of sediment left by a stream on the stream's channel or floodplain.

alpine glacier

A mountain glacier that is confined by highlands.

andesite

The dark, aphanitic, extrusive rock that has a silica content of about 60% and is the second most abundant volcanic rock. Andesites are found in large quantities in the Andes Mountains.

angle of repose

The maximum angle at which a pile of unconsolidated material can remain stable.

anthracite

A hard, jet-black coal that develops from lignite and bituminous coal through metamorphism, has a carbon content of 92% to 98%, and contains little or no gas. Anthracite burns with an extremely hot, blue flame and very little smoke, but it is difficult to ignite and both difficult and dangerous to mine.

anticline

A convex fold in rock, the central part of which contains the oldest section of rock. See also syncline.

aquiclude

An impermeable body of rock that may absorb water slowly but does not transmit it.

aquifer

A permeable body of rock or regolith that both stores and transports groundwater.

aquitard

A layer of rock having low permeability that stores groundwater but delays its flow.

arête

A sharp ridge of erosion-resistant rock formed between adjacent cirque glaciers.

aridity

index The ratio of a region's potential annual evaporation, as determined by its receipt of solar radiation, to its average annual precipitation.

arroyo

A small, deep, usually dry channel eroded by a short-lived or intermittent desert stream.

artesian

Of, being, or concerning an aquifer in which water rises to the surface due to pressure from overlying water.

asthenosphere

A layer of soft but solid, mobile rock comprising the lower part of the upper mantle from about 100 to 350 kilometers beneath the Earth's surface. See also lithosphere.

atoll

A circular reef that encloses a relatively shallow lagoon and extends from a very great depth to the sea surface. An atoll forms when an oceanic island ringed by a barrier reef sinks below sea level.

atom

The smallest particle that retains all the chemical properties of a given element.

atomic mass

1. The sum of protons and neutrons in an atom's nucleus. 2. The combined mass of all the particles in a given atom.

atomic number

The number of protons in the nucleus of a given atom. Elements are distinguished from each other by their at-omic numbers.

Glossary - Genetic (U-Z)

2008-03-23T04:33:00.001-07:00

Uracil

A nitrogenous base normally found in RNA but not DNA; uracil is capable of forming a base pair with adenine.
See also: base pair, nucleotide

Vector

See: cloning vector

Virus

A noncellular biological entity that can reproduce only within a host cell. Viruses consist of nucleic acid covered by protein; some animal viruses are also surrounded by membrane. Inside the infected cell, the virus uses the synthetic capability of the host to produce progeny virus.
See also: cloning vector

Western blot

A technique used to identify and locate proteins based on their ability to bind to specific antibodies.
See also: DNA, Northern blot, protein, RNA, Southern blotting

Wild type

The form of an organism that occurs most frequently in nature.

Working Draft DNA Sequence

See: Draft DNA Sequence

X chromosome

One of the two sex chromosomes, X and Y.
See also: Y chromosome, sex chromosome

Xenograft

Tissue or organs from an individual of one species transplanted into or grafted onto an organism of another species, genus, or family. A common example is the use of pig heart valves in humans.

Y chromosome

One of the two sex chromosomes, X and Y.
See also: X chromosome, sex chromosome

Yeast artificial chromosome (YAC)

Constructed from yeast DNA, it is a vector used to clone large DNA fragments.
See also: cloning vector, cosmid

Zinc-finger protein

A secondary feature of some proteins containing a zinc atom; a DNA-binding protein.

Glossary - Genetic (T)

2008-03-23T04:30:00.000-07:00

Tandem repeat sequences

Multiple copies of the same base sequence on a chromosome; used as markers in physical mapping.
See also: physical map

Targeted mutagenesis

Deliberate change in the genetic structure directed at a specific site on the chromosome. Used in research to determine the targeted region's function.
See also: mutation, polymorphism

Technology transfer

The process of transferring scientific findings from research laboratories to the commercial sector.

Telomerase

The enzyme that directs the replication of telomeres.

Telomere

The end of a chromosome. This specialized structure is involved in the replication and stability of linear DNA molecules.
See also: DNA replication

Teratogenic

Substances such as chemicals or radiation that cause abnormal development of a embryo.
See also: mutatgen

Thymine (T)

A nitrogenous base, one member of the base pair AT (adenine-thymine).
See also: base pair, nucleotide

Toxicogenomics

The study of how genomes respond to environmental stressors or toxicants. Combines genome-wide mRNA expression profiling with protein expression patterns using bioinformatics to understand the role of gene-environment interactions in disease and dysfunction.

Transcription

The synthesis of an RNA copy from a sequence of DNA (a gene); the first step in gene expression.
See also: translation

Transcription factor

A protein that binds to regulatory regions and helps control gene expression.

Transcriptome

The full complement of activated genes, mRNAs, or transcripts in a particular tissue at a particular time

Transfection

The introduction of foreign DNA into a host cell.
See also: cloning vector, gene therapy

Transfer RNA (tRNA)

A class of RNA having structures with triplet nucleotide sequences that are complementary to the triplet nucleotide coding sequences of mRNA. The role of tRNAs in protein synthesis is to bond with amino acids and transfer them to the ribosomes, where proteins are assembled according to the genetic code carried by mRNA.

Transformation

A process by which the genetic material carried by an individual cell is altered by incorporation of exogenous DNA into its genome.

Transgenic

An experimentally produced organism in which DNA has been artificially introduced and incorporated into the organism's germ line.
See also: cell, DNA, gene, nucleus, germ line

Translation

The process in which the genetic code carried by mRNA directs the synthesis of proteins from amino acids.
See also: transcription

Translocation

A mutation in which a large segment of one chromosome breaks off and attaches to another chromosome.
See also: mutation

Transposable element

A class of DNA sequences that can move from one chromosomal site to another.

Trisomy

Possessing three copies of a particular chromosome instead of the normal two copies.
See also: cell, gene, gene expression, chromosome

Glossary - Genetic (S)

2008-03-23T04:28:00.000-07:00

Sanger sequencing

A widely used method of determining the order of bases in DNA.
See also: sequencing, shotgun sequencing

Satellite

A chromosomal segment that branches off from the rest of the chromosome but is still connected by a thin filament or stalk.

Scaffold

In genomic mapping, a series of contigs that are in the right order but not necessarily connected in one continuous stretch of sequence.

Segregation

The normal biological process whereby the two pieces of a chromosome pair are separated during meiosis and randomly distributed to the germ cells.

Sequence

See: base sequence

Sequence assembly

A process whereby the order of multiple sequenced DNA fragments is determined.

Sequence tagged site (STS)

Short (200 to 500 base pairs) DNA sequence that has a single occurrence in the human genome and whose location and base sequence are known. Detectable by polymerase chain reaction, STSs are useful for localizing and orienting the mapping and sequence data reported from many different laboratories and serve as landmarks on the developing physical map of the human genome. Expressed sequence tags (ESTs) are STSs derived from cDNAs.

Sequencing

Determination of the order of nucleotides (base sequences) in a DNA or RNA molecule or the order of amino acids in a protein.

Sequencing technology

The instrumentation and procedures used to determine the order of nucleotides in DNA.

Sex chromosome

The X or Y chromosome in human beings that determines the sex of an individual. Females have two X chromosomes in diploid cells; males have an X and a Y chromosome. The sex chromosomes comprise the 23rd chromosome pair in a karyotype.
See also: autosome

Sex-linked

Traits or diseases associated with the X or Y chromosome; generally seen in males.
See also: gene, mutation, sex chromosome

Shotgun method

Sequencing method that involves randomly sequenced cloned pieces of the genome, with no foreknowledge of where the piece originally came from. This can be contrasted with "directed" strategies, in which pieces of DNA from known chromosomal locations are sequenced. Because there are advantages to both strategies, researchers use both random (or shotgun) and directed strategies in combination to sequence the human genome.
See also: library, genomic library

Single nucleotide polymorphism (SNP)

DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence is altered.
See also: mutation, polymorphism, single-gene disorder

Single-gene disorder

Hereditary disorder caused by a mutant allele of a single gene (e.g., Duchenne muscular dystrophy, retinoblastoma, sickle cell disease).
See also: polygenic disorders

Somatic cell

Any cell in the body except gametes and their precursors.
See also: gamete

Somatic cell gene therapy

Incorporating new genetic material into cells for therapeutic purposes. The new genetic material cannot be passed to offspring.
See also: gene therapy

Somatic cell genetic mutation

A change in the genetic structure that is neither inherited nor passed to offspring. Also called acquired mutations.
See also: germ line genetic mutation

Southern blotting

Transfer by absorption of DNA fragments separated in electrophoretic gels to membrane filters for detection of specific base sequences by radio-labeled complementary probes.

Spectral karyotype (SKY)

A graphic of all an organism's chromosomes, each labeled with a different color. Useful for identifying chromosomal abnormalities.
See also: chromosome

Splice site

Location in the DNA sequence where RNA removes the noncoding areas to form a continuous gene transcript for translation into a protein.

Sporadic cancer

Cancer that occurs randomly and is not inherited from parents. Caused by DNA changes in one cell that grows and divides, spreading throughout the body.
See also: hereditary cancer

Stem cell

Undifferentiated, primitive cells in the bone marrow that have the ability both to multiply and to differentiate into specific blood cells.

Structural genomics

The effort to determine the 3D structures of large numbers of proteins using both experimental techniques and computer simulation

Substitution

In genetics, a type of mutation due to replacement of one nucleotide in a DNA sequence by another nucleotide or replacement of one amino acid in a protein by another amino acid.
See also: mutation

Suppressor gene

A gene that can suppress the action of another gene.

Syndrome

The group or recognizable pattern of symptoms or abnormalities that indicate a particular trait or disease.

Syngeneic

Genetically identical members of the same species.

Synteny

Genes occurring in the same order on chromosomes of different species.
See also: linkage, conserved sequence

Glossary - Genetic (R)

2008-03-23T04:26:00.000-07:00

Radiation hybrid

A hybrid cell containing small fragments of irradiated human chromosomes. Maps of irradiation sites on chromosomes for the human, rat, mouse, and other genomes provide important markers, allowing the construction of very precise STS maps indispensable to studying multifactorial diseases.
See also: sequence tagged site

Rare-cutter enzyme

See: restriction-enzyme cutting site

Recessive gene

A gene which will be expressed only if there are 2 identical copies or, for a male, if one copy is present on the X chromosome.

Reciprocal translocation

When a pair of chromosomes exchange exactly the same length and area of DNA. Results in a shuffling of genes.

Recombinant clone

Clone containing recombinant DNA molecules.
See also: recombinant DNA technology

Recombinant DNA molecules

A combination of DNA molecules of different origin that are joined using recombinant DNA technologies.

Recombinant DNA technology

Procedure used to join together DNA segments in a cell-free system (an environment outside a cell or organism). Under appropriate conditions, a recombinant DNA molecule can enter a cell and replicate there, either autonomously or after it has become integrated into a cellular chromosome.

Recombination

The process by which progeny derive a combination of genes different from that of either parent. In higher organisms, this can occur by crossing over.
See also: crossing over, mutation

Regulatory region or sequence

A DNA base sequence that controls gene expression.

Repetitive DNA

Sequences of varying lengths that occur in multiple copies in the genome; it represents much of the human genome.

Reporter gene

See: marker

Resolution

Degree of molecular detail on a physical map of DNA, ranging from low to high.

Restriction enzyme, endonuclease

A protein that recognizes specific, short nucleotide sequences and cuts DNA at those sites. Bacteria contain over 400 such enzymes that recognize and cut more than 100 different DNA sequences.
See also: restriction enzyme cutting site

Restriction fragment length polymorphism (RFLP)

Variation between individuals in DNA fragment sizes cut by specific restriction enzymes; polymorphic sequences that result in RFLPs are used as markers on both physical maps and genetic linkage maps. RFLPs usually are caused by mutation at a cutting site.
See also: marker, polymorphism

Restriction-enzyme cutting site

A specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g., every several hundred base pairs); others much less frequently (rare-cutter; e.g., every 10,000 base pairs).

Retroviral infection

The presence of retroviral vectors, such as some viruses, which use their recombinant DNA to insert their genetic material into the chromosomes of the host's cells. The virus is then propogated by the host cell.

Reverse transcriptase

An enzyme used by retroviruses to form a complementary DNA sequence (cDNA) from their RNA. The resulting DNA is then inserted into the chromosome of the host cell.

Ribonucleotide

See: nucleotide

Ribose

The five-carbon sugar that serves as a component of RNA.
See also: ribonucleic acid, deoxyribose

Ribosomal RNA (rRNA)

A class of RNA found in the ribosomes of cells.

Ribosomes

Small cellular components composed of specialized ribosomal RNA and protein; site of protein synthesis.
See also: RNA

Risk communication

In genetics, a process in which a genetic counselor or other medical professional interprets genetic test results and advises patients of the consequences for them and their offspring.

RNA (Ribonucleic acid)

A chemical found in the nucleus and cytoplasm of cells; it plays an important role in protein synthesis and other chemical activities of the cell. The structure of RNA is similar to that of DNA. There are several classes of RNA molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each serving a different purpose.

Glossary - Genetic (P)

2008-03-23T04:24:00.000-07:00

P1-derived artificial chromosome (PAC)

One type of vector used to clone DNA fragments (100- to 300-kb insert size; average, 150 kb) in Escherichia coli cells. Based on bacteriophage (a virus) P1 genome.
See also: cloning vector

Patent

In genetics, conferring the right or title to genes, gene variations, or identifiable portions of sequenced genetic material to an individual or organization.
See also: gene

Pedigree

A family tree diagram that shows how a particular genetic trait or disease has been inherited.
See also: inherit

Penetrance

The probability of a gene or genetic trait being expressed. "Complete" penetrance means the gene or genes for a trait are expressed in all the population who have the genes. "Incomplete" penetrance means the genetic trait is expressed in only part of the population. The percent penetrance also may change with the age range of the population.

Peptide

Two or more amino acids joined by a bond called a "peptide bond."
See also: polypeptide

Phage

A virus for which the natural host is a bacterial cell.

Pharmacogenomics

The study of the interaction of an individual's genetic makeup and response to a drug.

Phenocopy

A trait not caused by inheritance of a gene but appears to be identical to a genetic trait.

Phenotype

The physical characteristics of an organism or the presence of a disease that may or may not be genetic.
See also: genotype

Physical map

A map of the locations of identifiable landmarks on DNA (e.g., restriction-enzyme cutting sites, genes), regardless of inheritance. Distance is measured in base pairs. For the human genome, the lowest-resolution physical map is the banding patterns on the 24 different chromosomes; the highest-resolution map is the complete nucleotide sequence of the chromosomes.

Plasmid

Autonomously replicating extra-chromosomal circular DNA molecules, distinct from the normal bacterial genome and nonessential for cell survival under nonselective conditions. Some plasmids are capable of integrating into the host genome. A number of artificially constructed plasmids are used as cloning vectors.

Pleiotropy

One gene that causes many different physical traits such as multiple disease symptoms.

Pluripotency

The potential of a cell to develop into more than one type of mature cell, depending on environment.

Polygenic disorder

Genetic disorder resulting from the combined action of alleles of more than one gene (e.g., heart disease, diabetes, and some cancers). Although such disorders are inherited, they depend on the simultaneous presence of several alleles; thus the hereditary patterns usually are more complex than those of single-gene disorders.
See also: single-gene disorder

Polymerase chain reaction (PCR)

A method for amplifying a DNA base sequence using a heat-stable polymerase and two 20-base primers, one complementary to the (+) strand at one end of the sequence to be amplified and one complementary to the (-) strand at the other end. Because the newly synthesized DNA strands can subsequently serve as additional templates for the same primer sequences, successive rounds of primer annealing, strand elongation, and dissociation produce rapid and highly specific amplification of the desired sequence. PCR also can be used to detect the existence of the defined sequence in a DNA sample.

Polymerase, DNA or RNA

Enzyme that catalyzes the synthesis of nucleic acids on preexisting nucleic acid templates, assembling RNA from ribonucleotides or DNA from deoxyribonucleotides.

Polymorphism

Difference in DNA sequence among individuals that may underlie differences in health. Genetic variations occurring in more than 1% of a population would be considered useful polymorphisms for genetic linkage analysis.
See also: mutation

Polypeptide

A protein or part of a protein made of a chain of amino acids joined by a peptide bond.

Population genetics

The study of variation in genes among a group of individuals.

Positional cloning

A technique used to identify genes, usually those that are associated with diseases, based on their location on a chromosome.

Premature chromosome condensation (PCC)

A method of studying chromosomes in the interphase stage of the cell cycle.

Primer

Short preexisting polynucleotide chain to which new deoxyribonucleotides can be added by DNA polymerase.

Privacy

In genetics, the right of people to restrict access to their genetic information.

Probe

Single-stranded DNA or RNA molecules of specific base sequence, labeled either radioactively or immunologically, that are used to detect the complementary base sequence by hybridization.

Prokaryote

Cell or organism lacking a membrane-bound, structurally discrete nucleus and other subcellular compartments. Bacteria are examples of prokaryotes.
See also: chromosome, eukaryote

Promoter

A DNA site to which RNA polymerase will bind and initiate transcription.

Pronucleus

The nucleus of a sperm or egg prior to fertilization.
See also: nucleus, transgenic

Protein

A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene that codes for the protein. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs; and each protein has unique functions. Examples are hormones, enzymes, and antibodies.

Proteome

Proteins expressed by a cell or organ at a particular time and under specific conditions.

Proteomics

The study of the full set of proteins encoded by a genome.

Pseudogene

A sequence of DNA similar to a gene but nonfunctional; probably the remnant of a once-functional gene that accumulated mutations.

Purine

A nitrogen-containing, double-ring, basic compound that occurs in nucleic acids. The purines in DNA and RNA are adenine and guanine.
See also: base pair

Pyrimidine

A nitrogen-containing, single-ring, basic compound that occurs in nucleic acids. The pyrimidines in DNA are cytosine and thymine; in RNA, cytosine and uracil.
See also: base pair

Glossary - Genetic (N-O)

2008-03-23T04:19:00.000-07:00

Nitrogenous base

A nitrogen-containing molecule having the chemical properties of a base. DNA contains the nitrogenous bases adenine (A), guanine (G), cytosine (C), and thymine (T).
See also: DNA

Northern blot

A gel-based laboratory procedure that locates mRNA sequences on a gel that are complementary to a piece of DNA used as a probe.
See also: DNA, library

Nuclear transfer

A laboratory procedure in which a cell's nucleus is removed and placed into an oocyte with its own nucleus removed so the genetic information from the donor nucleus controls the resulting cell. Such cells can be induced to form embryos. This process was used to create the cloned sheep "Dolly".
See also: cloning

Nucleic acid

A large molecule composed of nucleotide subunits.
See also: DNA

Nucleolar organizing region

A part of the chromosome containing rRNA genes.

Nucleotide

A subunit of DNA or RNA consisting of a nitrogenous base (adenine, guanine, thymine, or cytosine in DNA; adenine, guanine, uracil, or cytosine in RNA), a phosphate molecule, and a sugar molecule (deoxyribose in DNA and ribose in RNA). Thousands of nucleotides are linked to form a DNA or RNA molecule.
See also: DNA, base pair, RNA

Nucleus

The cellular organelle in eukaryotes that contains most of the genetic material.

Oligo

See: oligonucleotide

Oligogenic

A phenotypic trait produced by two or more genes working together.
See also: polygenic disorder

Oligonucleotide

A molecule usually composed of 25 or fewer nucleotides; used as a DNA synthesis primer.
See also: nucleotide

Oncogene

A gene, one or more forms of which is associated with cancer. Many oncogenes are involved, directly or indirectly, in controlling the rate of cell growth.

Open reading frame (ORF)

The sequence of DNA or RNA located between the start-code sequence (initiation codon) and the stop-code sequence (termination codon).

Operon

A set of genes transcribed under the control of an operator gene.

Overlapping clones

See: genomic library

Glossary - Genetic (M)

2008-03-23T04:16:00.000-07:00

Macrorestriction map

Map depicting the order of and distance between sites at which restriction enzymes cleave chromosomes.

Mapping

See: gene mapping, linkage map, physical map

Mapping population

The group of related organisms used in constructing a genetic map.

Marker

See: genetic marker

Mass spectrometry

An instrument used to identify chemicals in a substance by their mass and charge.

Megabase (Mb)

Unit of length for DNA fragments equal to 1 million nucleotides and roughly equal to 1 cM.
See also: centimorgan

Meiosis

The process of two consecutive cell divisions in the diploid progenitors of sex cells. Meiosis results in four rather than two daughter cells, each with a haploid set of chromosomes.
See also: mitosis

Mendelian inheritance

One method in which genetic traits are passed from parents to offspring. Named for Gregor Mendel, who first studied and recognized the existence of genes and this method of inheritance.
See also: autosomal dominant, recessive gene, sex-linked

Messenger RNA (mRNA)

RNA that serves as a template for protein synthesis.
See also: genetic code

Metaphase

A stage in mitosis or meiosis during which the chromosomes are aligned along the equatorial plane of the cell.

Microarray

Sets of miniaturized chemical reaction areas that may also be used to test DNA fragments, antibodies, or proteins.

Microbial genetics

The study of genes and gene function in bacteria, archaea, and other microorganisms. Often used in research in the fields of bioremediation, alternative energy, and disease prevention.
See also: model organisms, biotechnology, bioremediation

Microinjection

A technique for introducing a solution of DNA into a cell using a fine microcapillary pipet.

Micronuclei

Chromosome fragments that are not incorporated into the nucleus at cell division.

Mitochondrial DNA

The genetic material found in mitochondria, the organelles that generate energy for the cell. Not inherited in the same fashion as nucleic DNA.
See also: cell, DNA, genome, nucleus

Mitosis

The process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell.
See also: meiosis

Model organisms

A laboratory animal or other organism useful for research.

Modeling

The use of statistical analysis, computer analysis, or model organisms to predict outcomes of research.

Molecular biology

The study of the structure, function, and makeup of biologically important molecules.

Molecular farming

The development of transgenic animals to produce human proteins for medical use.

Molecular genetics

The study of macromolecules important in biological inheritance.

Molecular medicine

The treatment of injury or disease at the molecular level. Examples include the use of DNA-based diagnostic tests or medicine derived from DNA sequence information.

Monogenic disorder

A disorder caused by mutation of a single gene.
See also: mutation, polygenic disorder

Monogenic inheritance

See: monogenic disorder

Monosomy

Possessing only one copy of a particular chromosome instead of the normal two copies.
See also: cell, chromosome, gene expression, trisomy

Morbid map

A diagram showing the chromosomal location of genes associated with disease.

Mouse model

See: model organisms

Multifactorial or multigenic disorder

See: polygenic disorder

Multiplexing

A laboratory approach that performs multiple sets of reactions in parallel (simultaneously); greatly increasing speed and throughput.

Murine

Organism in the genus Mus. A rat or mouse.

Mutagen

An agent that causes a permanent genetic change in a cell. Does not include changes occurring during normal genetic recombination.

Mutagenicity

The capacity of a chemical or physical agent to cause permanent genetic alterations.
See also: somatic cell genetic mutation

Mutation

Any heritable change in DNA sequence.
See also: polymorphism

Glossary - Genetic (J-L)

2008-03-23T04:10:00.000-07:00

Junk DNA

Stretches of DNA that do not code for genes; most of the genome consists of so-called junk DNA which may have regulatory and other functions. Also called non-coding DNA.

Karyotype

A photomicrograph of an individual's chromosomes arranged in a standard format showing the number, size, and shape of each chromosome type; used in low-resolution physical mapping to correlate gross chromosomal abnormalities with the characteristics of specific diseases.

Kilobase (kb)

Unit of length for DNA fragments equal to 1000 nucleotides.

Knockout

Deactivation of specific genes; used in laboratory organisms to study gene function.
See also: gene, locus, model organisms

Library

An unordered collection of clones (i.e., cloned DNA from a particular organism) whose relationship to each other can be established by physical mapping.
See also: genomic library, arrayed library

Linkage

The proximity of two or more markers (e.g., genes, RFLP markers) on a chromosome; the closer the markers, the lower the probability that they will be separated during DNA repair or replication processes (binary fission in prokaryotes, mitosis or meiosis in eukaryotes), and hence the greater the probability that they will be inherited together.

Linkage disequilibrium

Where alleles occur together more often than can be accounted for by chance. Indicates that the two alleles are physically close on the DNA strand.
See also: Mendelian inheritance

Linkage map

A map of the relative positions of genetic loci on a chromosome, determined on the basis of how often the loci are inherited together. Distance is measured in centimorgans (cM).

Localize

Determination of the original position (locus) of a gene or other marker on a chromosome.

Locus (pl. loci)

The position on a chromosome of a gene or other chromosome marker; also, the DNA at that position. The use of locus is sometimes restricted to mean expressed DNA regions.
See also: gene expression

Long-Range Restriction Mapping

Restriction enzymes are proteins that cut DNA at precise locations. Restriction maps depict the chromosomal positions of restriction-enzyme cutting sites. These are used as biochemical "signposts," or markers of specific areas along the chromosomes. The map will detail the positions where the DNA molecule is cut by particular restriction enzymes.

Glossary - Genetic (I)

2008-03-23T04:08:00.000-07:00

Identical twin

Twins produced by the division of a single zygote; both have identical genotypes.
See also: fraternal twin

Immunotherapy

Using the immune system to treat disease, for example, in the development of vaccines. May also refer to the therapy of diseases caused by the immune system.
See also: cancer

Imprinting

A phenomenon in which the disease phenotype depends on which parent passed on the disease gene. For instance, both Prader-Willi and Angelman syndromes are inherited when the same part of chromosome 15 is missing. When the father's complement of 15 is missing, the child has Prader-Willi, but when the mother's complement of 15 is missing, the child has Angelman syndrome.

In situ hybridization

Use of a DNA or RNA probe to detect the presence of the complementary DNA sequence in cloned bacterial or cultured eukaryotic cells.

In vitro

Studies performed outside a living organism such as in a laboratory.

In vivo

Studies carried out in living organisms.

Independent assortment

During meiosis each of the two copies of a gene is distributed to the germ cells independently of the distribution of other genes.
See also: linkage

Informatics

See: bioinformatics

Informed consent

An individual willingly agrees to participate in an activity after first being advised of the risks and benefits.
See also: privacy

Inherit

In genetics, to receive genetic material from parents through biological processes.

Inherited

See: inherit

Insertion

A chromosome abnormality in which a piece of DNA is incorporated into a gene and thereby disrupts the gene's normal function.
See also: chromosome, DNA, gene, mutation

Insertional mutation

See: insertion

Intellectual property rights

Patents, copyrights, and trademarks.
See also: patent

Interference

One crossover event inhibits the chances of another crossover event. Also known as positive interference. Negative interference increases the chance of a second crossover.
See also: crossing over

Interphase

The period in the cell cycle when DNA is replicated in the nucleus; followed by mitosis.

Intron

DNA sequence that interrupts the protein-coding sequence of a gene; an intron is transcribed into RNA but is cut out of the message before it is translated into protein.
See also: exon

Isoenzyme

An enzyme performing the same function as another enzyme but having a different set of amino acids. The two enzymes may function at different speeds.

Glossary - Genetic (H)

2008-03-23T04:05:00.000-07:00

Haploid

A single set of chromosomes (half the full set of genetic material) present in the egg and sperm cells of animals and in the egg and pollen cells of plants. Human beings have 23 chromosomes in their reproductive cells.
See also: diploid

Haplotype

A way of denoting the collective genotype of a number of closely linked loci on a chromosome.

Hemizygous

Having only one copy of a particular gene. For example, in humans, males are hemizygous for genes found on the Y chromosome.

Hereditary cancer

Cancer that occurs due to the inheritance of an altered gene within a family.
See also: sporadic cancer

Heterozygosity

The presence of different alleles at one or more loci on homologous chromosomes.

Heterozygote

See: heterozygosity

Highly conserved sequence

DNA sequence that is very similar across several different types of organisms.
See also: gene, mutation

High-throughput sequencing

A fast method of determining the order of bases in DNA.
See also: sequencing

Homeobox

A short stretch of nucleotides whose base sequence is virtually identical in all the genes that contain it. Homeoboxes have been found in many organisms from fruit flies to human beings. In the fruit fly, a homeobox appears to determine when particular groups of genes are expressed during development.

Homolog

A member of a chromosome pair in diploid organisms or a gene that has the same origin and functions in two or more species.

Homologous chromosome

Chromosome containing the same linear gene sequences as another, each derived from one parent.

Homologous recombination

Swapping of DNA fragments between paired chromosomes.

Homology

Similarity in DNA or protein sequences between individuals of the same species or among different species.

Homozygote

An organism that has two identical alleles of a gene.
See also: heterozygote

Homozygous

See: homozygote

Human artificial chromosome (HAC)

A vector used to hold large DNA fragments.
See also: chromosome, DNA

Human gene therapy

See: gene therapy

Human Genome Initiative

Collective name for several projects begun in 1986 by DOE to create an ordered set of DNA segments from known chromosomal locations, develop new computational methods for analyzing genetic map and DNA sequence data, and develop new techniques and instruments for detecting and analyzing DNA. This DOE initiative is now known as the Human Genome Program. The joint national effort, led by DOE and NIH, is known as the Human Genome Project.

Human Genome Project (HGP)

Formerly titled Human Genome Initiative.
See also: Human Genome Initiative

Hybrid

The offspring of genetically different parents.
See also: heterozygote

Hybridization

The process of joining two complementary strands of DNA or one each of DNA and RNA to form a double-stranded molecule.

Glossary - Genetic (G)

2008-03-23T04:02:00.000-07:00

Gamete

Mature male or female reproductive cell (sperm or ovum) with a haploid set of chromosomes (23 for humans).

GC-rich area

Many DNA sequences carry long stretches of repeated G and C which often indicate a gene-rich region.

Gel electrophoresis

See: electrophoresis

Gene

The fundamental physical and functional unit of heredity. A gene is an ordered sequence of nucleotides located in a particular position on a particular chromosome that encodes a specific functional product (i.e., a protein or RNA molecule).
See also: gene expression

Gene amplification

Repeated copying of a piece of DNA; a characteristic of tumor cells.
See also: gene, oncogene

Gene chip technology

Development of cDNA microarrays from a large number of genes. Used to monitor and measure changes in gene expression for each gene represented on the chip.

Gene expression

The process by which a gene's coded information is converted into the structures present and operating in the cell. Expressed genes include those that are transcribed into mRNA and then translated into protein and those that are transcribed into RNA but not translated into protein (e.g., transfer and ribosomal RNAs).

Gene family

Group of closely related genes that make similar products.

Gene library

See: genomic library

Gene mapping

Determination of the relative positions of genes on a DNA molecule (chromosome or plasmid) and of the distance, in linkage units or physical units, between them.

Gene pool

All the variations of genes in a species.
See also: allele, gene, polymorphism

Gene prediction

Predictions of possible genes made by a computer program based on how well a stretch of DNA sequence matches known gene sequences

Gene product

The biochemical material, either RNA or protein, resulting from expression of a gene. The amount of gene product is used to measure how active a gene is; abnormal amounts can be correlated with disease-causing alleles.

Gene testing

See: genetic testing, genetic screening

Gene therapy

An experimental procedure aimed at replacing, manipulating, or supplementing nonfunctional or misfunctioning genes with healthy genes.
See also: gene, inherit, somatic cell gene therapy, germ line gene therapy

Gene transfer

Incorporation of new DNA into and organism's cells, usually by a vector such as a modified virus. Used in gene therapy.
See also: mutation, gene therapy, vector

Genetic code

The sequence of nucleotides, coded in triplets (codons) along the mRNA, that determines the sequence of amino acids in protein synthesis. A gene's DNA sequence can be used to predict the mRNA sequence, and the genetic code can in turn be used to predict the amino acid sequence.

Genetic counseling

Provides patients and their families with education and information about genetic-related conditions and helps them make informed decisions.

Genetic discrimination

Prejudice against those who have or are likely to develop an inherited disorder.

Genetic engineering

Altering the genetic material of cells or organisms to enable them to make new substances or perform new functions.

Genetic engineering technology

See: recombinant DNA technology

Genetic illness

Sickness, physical disability, or other disorder resulting from the inheritance of one or more deleterious alleles.

Genetic informatics

See: bioinformatics

Genetic map

See: linkage map

Genetic marker

A gene or other identifiable portion of DNA whose inheritance can be followed.
See also: chromosome, DNA, gene, inherit

Genetic material

See: genome

Genetic mosaic

An organism in which different cells contain different genetic sequence. This can be the result of a mutation during development or fusion of embryos at an early developmental stage.

Genetic polymorphism

Difference in DNA sequence among individuals, groups, or populations (e.g., genes for blue eyes versus brown eyes).

Genetic predisposition

Susceptibility to a genetic disease. May or may not result in actual development of the disease.

Genetic screening

Testing a group of people to identify individuals at high risk of having or passing on a specific genetic disorder.

Genetic testing

Analyzing an individual's genetic material to determine predisposition to a particular health condition or to confirm a diagnosis of genetic disease.

Genetics

The study of inheritance patterns of specific traits.

Genome

All the genetic material in the chromosomes of a particular organism; its size is generally given as its total number of base pairs.

Genome project

Research and technology-development effort aimed at mapping and sequencing the genome of human beings and certain model organisms.
See also: Human Genome Initiative

Genomic library

A collection of clones made from a set of randomly generated overlapping DNA fragments that represent the entire genome of an organism.
See also: library, arrayed library

Genomic sequence

See: DNA

Genomics

The study of genes and their function.

Genotype

The genetic constitution of an organism, as distinguished from its physical appearance (its phenotype).

Germ cell

Sperm and egg cells and their precursors. Germ cells are haploid and have only one set of chromosomes (23 in all), while all other cells have two copies (46 in all).

Germ line

The continuation of a set of genetic information from one generation to the next.
See also: inherit

Germ line gene therapy

An experimental process of inserting genes into germ cells or fertilized eggs to cause a genetic change that can be passed on to offspring. May be used to alleviate effects associated with a genetic disease.
See also: genomics, somatic cell gene therapy.

Germ line genetic mutation

See: mutation

Guanine (G)

A nitrogenous base, one member of the base pair GC (guanine and cytosine) in DNA.
See also: base pair, nucleotide

Gyandromorph

Organisms that have both male and female cells and therefore express both male and female characteristics.

Glossary - Genetic (F)

2008-03-23T03:57:00.000-07:00

Filial generation (F1, F2)

Each generation of offspring in a breeding program, designated F1, F2, etc.

Fingerprinting

In genetics, the identification of multiple specific alleles on a person's DNA to produce a unique identifier for that person.
See also: forensics

Finished DNA Sequence

High-quality, low error, gap-free DNA sequence of the human genome. Achieving this ultimate 2003 HGP goal requires additional sequencing to close gaps, reduce ambiguities, and allow for only a single error every 10,000 bases, the agreed-upon standard for HGP finished sequence.
See also: sequencing, draft sequence

Flow cytometry

Analysis of biological material by detection of the light-absorbing or fluorescing properties of cells or subcellular fractions (i.e., chromosomes) passing in a narrow stream through a laser beam. An absorbance or fluorescence profile of the sample is produced. Automated sorting devices, used to fractionate samples, sort successive droplets of the analyzed stream into different fractions depending on the fluorescence emitted by each droplet.

Flow karyotyping

Use of flow cytometry to analyze and separate chromosomes according to their DNA content.

Fluorescence in situ hybridization (FISH)

A physical mapping approach that uses fluorescein tags to detect hybridization of probes with metaphase chromosomes and with the less-condensed somatic interphase chromatin.

Forensics

The use of DNA for identification. Some examples of DNA use are to establish paternity in child support cases; establish the presence of a suspect at a crime scene, and identify accident victims.

Fraternal twin

Siblings born at the same time as the result of fertilization of two ova by two sperm. They share the same genetic relationship to each other as any other siblings.
See also: identical twin

Full gene sequence

The complete order of bases in a gene. This order determines which protein a gene will produce.

Functional genomics

The study of genes, their resulting proteins, and the role played by the proteins the body's biochemical processes.

Glossary - Genetic (E)

2008-03-23T03:50:00.000-07:00

Electrophoresis

A method of separating large molecules (such as DNA fragments or proteins) from a mixture of similar molecules. An electric current is passed through a medium containing the mixture, and each kind of molecule travels through the medium at a different rate, depending on its electrical charge and size. Agarose and acrylamide gels are the media commonly used for electrophoresis of proteins and nucleic acids.

Electroporation

A process using high-voltage current to make cell membranes permeable to allow the introduction of new DNA; commonly used in recombinant DNA technology.
See also: transfection

Embryonic stem (ES) cells

An embryonic cell that can replicate indefinitely, transform into other types of cells, and serve as a continuous source of new cells.

Endonuclease

See: restriction enzyme

Enzyme

A protein that acts as a catalyst, speeding the rate at which a biochemical reaction proceeds but not altering the direction or nature of the reaction.

Epistasis

One gene interfers with or prevents the expression of another gene located at a different locus.

Escherichia coli

Common bacterium that has been studied intensively by geneticists because of its small genome size, normal lack of pathogenicity, and ease of growth in the laboratory.

Eugenics

The study of improving a species by artificial selection; usually refers to the selective breeding of humans.

Eukaryote

Cell or organism with membrane-bound, structurally discrete nucleus and other well-developed subcellular compartments. Eukaryotes include all organisms except viruses, bacteria, and bluegreen algae.
See also: prokaryote, chromosome.

Evolutionarily conserved

See: conserved sequence

Exogenous DNA

DNA originating outside an organism that has been introducted into the organism.

Exon

The protein-coding DNA sequence of a gene.
See also: intron

Exonuclease

An enzyme that cleaves nucleotides sequentially from free ends of a linear nucleic acid substrate.

Expressed gene

See: gene expression

Expressed sequence tag (EST)

A short strand of DNA that is a part of a cDNA molecule and can act as identifier of a gene. Used in locating and mapping genes.
See also: cDNA, sequence tagged site

Glossary - Genetic (D)

2008-03-23T03:34:00.001-07:00

Data warehouse

A collection of databases, data tables, and mechanisms to access the data on a single subject.

Deletion

A loss of part of the DNA from a chromosome; can lead to a disease or abnormality.
See also: chromosome, mutation

Deletion map

A description of a specific chromosome that uses defined mutations --specific deleted areas in the genome-- as 'biochemical signposts,' or markers for specific areas.

Deoxyribonucleotide

See: nucleotide

Deoxyribose

A type of sugar that is one component of DNA (deoxyribonucleic acid).

Diploid

A full set of genetic material consisting of paired chromosomes, one from each parental set. Most animal cells except the gametes have a diploid set of chromosomes. The diploid human genome has 46 chromosomes.
See also: haploid

Directed evolution

A laboratory process used on isolated molecules or microbes to cause mutations and identify subsequent adaptations to novel environments.

Directed mutagenesis

Alteration of DNA at a specific site and its reinsertion into an organism to study any effects of the change.

Directed sequencing

Successively sequencing DNA from adjacent stretches of chromosome.

Disease-associated genes

Alleles carrying particular DNA sequences associated with the presence of disease.

DNA (deoxyribonucleic acid)

The molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases adenine (A), guanine (G), cytosine (C), and thymine (T). In nature, base pairs form only between A and T and between G and C; thus the base sequence of each single strand can be deduced from that of its partner.

DNA bank

A service that stores DNA extracted from blood samples or other human tissue.

DNA probe

See: probe

DNA repair genes

Genes encoding proteins that correct errors in DNA sequencing.

DNA replication

The use of existing DNA as a template for the synthesis of new DNA strands. In humans and other eukaryotes, replication occurs in the cell nucleus.

DNA sequence

The relative order of base pairs, whether in a DNA fragment, gene, chromosome, or an entire genome.
See also: base sequence analysis

Domain

A discrete portion of a protein with its own function. The combination of domains in a single protein determines its overall function.

Dominant

An allele that is almost always expressed, even if only one copy is present.
See also: gene, genome

Double helix

The twisted-ladder shape that two linear strands of DNA assume when complementary nucleotides on opposing strands bond together.

Draft sequence

The sequence generated by the HGP as of June 2000 that, while incomplete, offers a virtual road map to an estimated 95% of all human genes. Draft sequence data are mostly in the form of 10,000 base pair-sized fragments whose approximate chromosomal locations are known.
See also: sequencing, finished DNA sequence, working draft DNA sequence

Glossary - Genetic (C)

2008-03-23T03:30:00.000-07:00

Cancer

Diseases in which abnormal cells divide and grow unchecked. Cancer can spread from its original site to other parts of the body and can be fatal.
See also: hereditary cancer, sporadic cancer

Candidate gene

A gene located in a chromosome region suspected of being involved in a disease.
See also: positional cloning, protein

Capillary array

Gel-filled silica capillaries used to separate fragments for DNA sequencing. The small diameter of the capillaries permit the application of higher electric fields, providing high speed, high throughput separations that are significantly faster than traditional slab gels.

Carcinogen

Something which causes cancer to occur by causing changes in a cell's DNA.
See also: mutagene

Carrier

An individual who possesses an unexpressed, recessive trait.

cDNA library

A collection of DNA sequences that code for genes. The sequences are generated in the laboratory from mRNA sequences.
See also: messenger RNA

Cell

The basic unit of any living organism that carries on the biochemical processes of life.
See also: genome, nucleus

Centimorgan (cM)

A unit of measure of recombination frequency. One centimorgan is equal to a 1% chance that a marker at one genetic locus will be separated from a marker at a second locus due to crossing over in a single generation. In human beings, one centimorgan is equivalent, on average, to one million base pairs.
See also: megabase

Centromere

A specialized chromosome region to which spindle fibers attach during cell division.

Chimera (pl. chimaera)

An organism that contains cells or tissues with a different genotype. These can be mutated cells of the host organism or cells from a different organism or species.

Chimeraplasty

An experimental targeted repair process in which a desirable sequence of DNA is combined with RNA to form a chimeraplast. These molecules bind selectively to the target DNA. Once bound, the chimeraplast activates a naturally occurring gene-correcting mechanism. Does not use viral or other conventional gene-delivery vectors.
See also: gene therapy, cloning vector

Chloroplast chromosome

Circular DNA found in the photosynthesizing organelle (chloroplast) of plants instead of the cell nucleus where most genetic material is located.

Chromomere

One of the serially aligned beads or granules of a eukaryotic chromosome, resulting from local coiling of a continuous DNA thread.

Chromosomal deletion

The loss of part of a chromosome's DNA.

Chromosomal inversion

Chromosome segments that have been turned 180 degrees. The gene sequence for the segment is reversed with respect to the rest of the chromosome.

Chromosome

The self-replicating genetic structure of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryotic genomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins.

Chromosome painting

Attachment of certain fluorescent dyes to targeted parts of the chromosome. Used as a diagnositic for particular diseases, e.g. types of leukemia.

Chromosome region p

A designation for the short arm of a chromosome.

Chromosome region q

A designation for the long arm of a chromosome.

Clone

An exact copy made of biological material such as a DNA segment (e.g., a gene or other region), a whole cell, or a complete organism.

Clone bank

See: genomic library

Cloning

Using specialized DNA technology to produce multiple, exact copies of a single gene or other segment of DNA to obtain enough material for further study. This process, used by researchers in the Human Genome Project, is referred to as cloning DNA. The resulting cloned (copied) collections of DNA molecules are called clone libraries. A second type of cloning exploits the natural process of cell division to make many copies of an entire cell. The genetic makeup of these cloned cells, called a cell line, is identical to the original cell. A third type of cloning produces complete, genetically identical animals such as the famous Scottish sheep, Dolly.
See also: cloning vector

Cloning vector

DNA molecule originating from a virus, a plasmid, or the cell of a higher organism into which another DNA fragment of appropriate size can be integrated without loss of the vector's capacity for self-replication; vectors introduce foreign DNA into host cells, where the DNA can be reproduced in large quantities. Examples are plasmids, cosmids, and yeast artificial chromosomes; vectors are often recombinant molecules containing DNA sequences from several sources.

Code

See: genetic code

Codominance

Situation in which two different alleles for a genetic trait are both expressed.
See also: autosomal dominant, recessive gene

Codon

See: genetic code

Coisogenic or congenic

Nearly identical strains of an organism; they vary at only a single locus.

Comparative genomics

The study of human genetics by comparisons with model organisms such as mice, the fruit fly, and the bacterium E. coli.

Complementary DNA (cDNA)

DNA that is synthesized in the laboratory from a messenger RNA template.

Complementary sequence

Nucleic acid base sequence that can form a double-stranded structure with another DNA fragment by following base-pairing rules (A pairs with T and C with G). The complementary sequence to GTAC for example, is CATG.

Complex trait

Trait that has a genetic component that does not follow strict Mendelian inheritance. May involve the interaction of two or more genes or gene-environment interactions.
See also: Mendelian inheritance, additive genetic effects

Computational biology

See: bioinformatics

Confidentiality

In genetics, the expectation that genetic material and the information gained from testing that material will not be available without the donor's consent.

Congenital

Any trait present at birth, whether the result of a genetic or nongenetic factor.
See also: birth defect

Conserved sequence

A base sequence in a DNA molecule (or an amino acid sequence in a protein) that has remained essentially unchanged throughout evolution.

Constitutive ablation

Gene expression that results in cell death.

Contig

Group of cloned (copied) pieces of DNA representing overlapping regions of a particular chromosome.

Contig map

A map depicting the relative order of a linked library of overlapping clones representing a complete chromosomal segment.

Cosmid

Artificially constructed cloning vector containing the cos gene of phage lambda. Cosmids can be packaged in lambda phage particles for infection into E. coli; this permits cloning of larger DNA fragments (up to 45kb) than can be introduced into bacterial hosts in plasmid vectors.

Crossing over

The breaking during meiosis of one maternal and one paternal chromosome, the exchange of corresponding sections of DNA, and the rejoining of the chromosomes. This process can result in an exchange of alleles between chromosomes.
See also: recombination

Cytogenetics

The study of the physical appearance of chromosomes.
See also: karyotype

Cytological band

An area of the chromosome that stains differently from areas around it.
See also: cytological map

Cytological map

A type of chromosome map whereby genes are located on the basis of cytological findings obtained with the aid of chromosome mutations.

Cytoplasmic (uniparental) inheritance

See: cytoplasmic trait

Cytoplasmic trait

A genetic characteristic in which the genes are found outside the nucleus, in chloroplasts or mitochondria. Results in offspring inheriting genetic material from only one parent.

Cytosine (C)

A nitrogenous base, one member of the base pair GC (guanine and cytosine) in DNA.
See also: base pair, nucleotide

Glossary - Genetic (B)

2008-03-23T03:28:00.000-07:00

Backcross

A cross between an animal that is heterozygous for alleles obtained from two parental strains and a second animal from one of those parental strains. Also used to describe the breeding protocol of an outcross followed by a backcross.
See also: model organisms

Bacterial artificial chromosome (BAC)

A vector used to clone DNA fragments (100- to 300-kb insert size; average, 150 kb) in Escherichia coli cells. Based on naturally occurring F-factor plasmid found in the bacterium E. coli.
See also: cloning vector

Bacteriophage

See: phage

Base

One of the molecules that form DNA and RNA molecules.
See also: nucleotide, base pair, base sequence

Base pair (bp)

Two nitrogenous bases (adenine and thymine or guanine and cytosine) held together by weak bonds. Two strands of DNA are held together in the shape of a double helix by the bonds between base pairs.

Base sequence

The order of nucleotide bases in a DNA molecule; determines structure of proteins encoded by that DNA.

Base sequence analysis

A method, sometimes automated, for determining the base sequence.

Behavioral genetics

The study of genes that may influence behavior.

Bioinformatics

The science of managing and analyzing biological data using advanced computing techniques. Especially important in analyzing genomic research data.
See also: informatics

Bioremediation

The use of biological organisms such as plants or microbes to aid in removing hazardous substances from an area.

Biotechnology

A set of biological techniques developed through basic research and now applied to research and product development. In particular, biotechnology refers to the use by industry of recombinant DNA, cell fusion, and new bioprocessing techniques.

Birth defect

Any harmful trait, physical or biochemical, present at birth, whether a result of a genetic mutation or some other nongenetic factor.
See also: congenital, gene, mutation, syndrome

BLAST

A computer program that identifies homologous (similar) genes in different organisms, such as human, fruit fly, or nematode.

Glossary - Genetic (A)

2008-03-23T03:15:00.000-07:00

Acquired genetic mutation

See: somatic cell genetic mutation

Additive genetic effects

When the combined effects of alleles at different loci are equal to the sum of their individual effects.
See also: anticipation, complex trait

Adenine (A)

A nitrogenous base, one member of the base pair AT (adenine-thymine).
See also: base pair, nucleotide

Affected relative pair

Individuals related by blood, each of whom is affected with the same trait. Examples are affected sibling, cousin, and avuncular pairs.
See also: avuncular relationship

Aggregation technique

A technique used in model organism studies in which embryos at the 8-cell stage of development are pushed together to yield a single embryo (used as an alternative to microinjection).
See also: model organisms

Allele

Alternative form of a genetic locus; a single allele for each locus is inherited from each parent (e.g., at a locus for eye color the allele might result in blue or brown eyes).
See also: locus, gene expression

Allogeneic

Variation in alleles among members of the same species.

Alternative splicing

Different ways of combining a gene's exons to make variants of the complete protein

Amino acid

Any of a class of 20 molecules that are combined to form proteins in living things. The sequence of amino acids in a protein and hence protein function are determined by the genetic code.

Amplification

An increase in the number of copies of a specific DNA fragment; can be in vivo or in vitro.
See also: cloning, polymerase chain reaction

Animal model

See: model organisms

Annotation

Adding pertinent information such as gene coded for, amino acid sequence, or other commentary to the database entry of raw sequence of DNA bases.
See also: bioinformatics

Anticipation

Each generation of offspring has increased severity of a genetic disorder; e.g., a grandchild may have earlier onset and more severe symptoms than the parent, who had earlier onset than the grandparent.
See also: additive genetic effects, complex trait

Antisense

Nucleic acid that has a sequence exactly opposite to an mRNA molecule made by the body; binds to the mRNA molecule to prevent a protein from being made.
See also: transcription

Apoptosis

Programmed cell death, the body's normal method of disposing of damaged, unwanted, or unneeded cells.
See also: cell

Arrayed library

Individual primary recombinant clones (hosted in phage, cosmid, YAC, or other vector) that are placed in two-dimensional arrays in microtiter dishes. Each primary clone can be identified by the identity of the plate and the clone location (row and column) on that plate. Arrayed libraries of clones can be used for many applications, including screening for a specific gene or genomic region of interest.
See also: library, genomic library, gene chip technology

Assembly

Putting sequenced fragments of DNA into their correct chromosomal positions.

Autoradiography

A technique that uses X-ray film to visualize radioactively labeled molecules or fragments of molecules; used in analyzing length and number of DNA fragments after they are separated by gel electrophoresis.

Autosomal dominant

A gene on one of the non-sex chromosomes that is always expressed, even if only one copy is present. The chance of passing the gene to offspring is 50% for each pregnancy.
See also: autosome, dominant, gene

Autosome

A chromosome not involved in sex determination. The diploid human genome consists of a total of 46 chromosomes: 22 pairs of autosomes, and 1 pair of sex chromosomes (the X and Y chromosomes).
See also: sex chromosome

Avuncular relationship

The genetic relationship between nieces and nephews and their aunts and uncles.

Glossary - Enginering (A-Z)

2008-03-23T02:56:00.000-07:00

A
Accumulator : akumulator
Accuray : kecermatan, ketelitian
Actual cost : biaya aktual
Actuator : penggiat
Adaptive integration : pengintegralan adaptif
Addend : tinambah
Adder : penambah
Adjacent angle : sudut damping
Adjoint : alih letak sekawan, adjoin
Adjoint operator : operator joint
Adjustment : penyesuaian
Admissible : terkenan, diperkenankan
Admittance : admitans
Agregate : agregat
Algebra : aljabar
Algorithm : algoritma
Alias : alias
Aliasing : pengaliasan
Alpha Error : galat alfa
Alternate exterior angle : sudut luar berseberangan
Alternate interior angle : sudut dalam berseberangan
Alternator : perangga, altenator
Alternating Current (AC) : arus rangga
Ambient space : ruang sekitar
Ambiguity : keambiguan
Analog : analog
Antifilter : antitapis
Antisymetric law : hukum antisimetrik
Aperiodic : tak berkala
Approach : mendekati, pendekatan
Approximate : menghampir
Armature : jangkar, almatur
Array : larik, susunan
Artificial cognition : pengenalan buatan
Assembler : perakit, asemblar
A-stability : kesetabilan-A
Asymptote : asimptote
Attenuating : melaif
Attenuation : laifan, atenuasi
Automatic abstracting : pengabstrakan automatik
Autoplotter : autopemlot
Average : rerata
Axonometric chart : bagan aksonometrik

B
Back-up file : berkas cadangan
Backward difference : beda mundur
Band : pita
Band-width : lebar pita
Basic assumption : anggapan dasar
Basic : basis
Batch monitor : monitor tumpak
Beam : berkas
Best payoff : langsaian terbaik
Bias : prasikap, bias
Blink : kedip
Block cutpoint paragraph : graf titik potong blok
Blok diagram : diagram blok
Bottom margin : tepi bawah
Bound : batas, had
Boundary : perbatasan, sempadan
Brainware : perangkat otak
Breakdown : dadal
Brightness : kecerahan
Buffer : penyangga, buffer
Busy probability : probabilitas sibuk
Byte : byte
By-pass : regatan

C
Canonical : kanonis
Capacitated network : jaringan berkapasitas
Capacitante : kapasitans
Carrier : pembawa
Cascade : riam
Cascade process : proses riam
Cash discount : diskonto tunai
Causal chain model : model penyebab rantai
Causal system : sistem kausal
Characteristic : karakteristik, ciri
Chart : bagan
Check bit : bit periksa
Chopper : pemenggal
Circuit : untai, sirkuit
Closure law : hukum ketertutupan
Cluster : gugus
Coaxial : sumbu,koaksial
Code : sandi
Coil : kumparan
Coincide : berimpit
Collinear : kolinear, segaris
Collumn : kolom, lajur
Commutative : komutatif, ulang-alik
Commutation : balik-urutan, komutasi
Commutator : komutator
Comparable : terbanding
Compatible : serasi
Compiler : kompilator
Complement : penyiku, pelengkap
Complex : kompleks
Compnent : komponen
Composite function : fungsi majemuk/komposit
Composition : susunan, komposisi
Computation : komputasi
Concept : konsep
Condition : syarat
Conductance : hantaran, konduktans
Confidence belt : jalur kepercayaan
Conformity : kecocokan
Congestion problem : masalah kesesakan
Congruence theorem : teorema kekongruenan
Conjugate : sekawan, konjugat
Consistence : kekonsistenan, konsistens
Constant : tetapan, konstan
Constraint : kendala
Contingency : kontingensi
Continuation : pengontinuan
Continum : malaran, kontinu
Continuous : kontinu, malar
Continuity : kemalaran
Contour : kontur
Contrat : pembanding, kontras
Control : kendali
Correlation : korelasi
Correspond to : berpadanan dengan
Covariance : peragam, kovarians
Counter : alat cacah
Curl of a vector : keikalan vektor
Cut off : penggalan, potongan
Cycle : siklus
Cyclic : siklik

D
Damped : teredam
Damped oscillation : ayunan teredam
Damping : redaman
Damping factor : faktor redaman
Debugging : pencarian kesalahan
Decay : pererasan
Decoder : dekoder
Decompose : urai
Default value : nilai lalai
Defective sample : contoh cacat
Definite : tertentu, definit
Definition : definisi
Degree : derajat
Delay : tunda
Design equation : persamaan rancangan
Deviation : simpangan
Device : piranti
Dichotomy : dikotomi, kedwicabangan
Difference : beda, diferens
Differential : diferensial
Digit : digit
Disc : 1. Cakram, 2. Disk
Discrete : diskret
Discharge : lucutan, luahan
Diskette : disket
Disposal policy : kebijakan pembuangan
Distortion : erotan, distorsi
Distribution : agihan, sebaran, distribusi
Distributed : teragih
Domain : ranah, domain
Drift : hanyutan
Dual : ganda, dual
Duality : kedualan, dualitas
Dummy : rekaan
Duodecimals : dua belasan-dua belasan, duodesimal

E
Echo : gema
Eigen value : eigennilai
Eigen vector : eigenvektor
Element : unsur
Embedding : pembenaman
Emission : pancaran, emisi
Emulator : emulator
Escape code : sandi lepasan
Energy : tenaga
Equilibrium : keseimbangan
Equivalent : setara
Error : galat
Error control : kendali galat
Estimate value : nilai dugaan
Estimation : pendugaan, estimasi
Etching : memunar
Exact : eksak
Excess : turah, lebih
Expectation : harapan
Explicit : eksplisit
Expression : ungkapan
Extreme : ekstremum

F
Failure rate : tingkat kegagalan
False : palsu
Feedback : umpan balik
Field : medan, lapangan
Filament : filamen
Filter : tapis, filter
Filter-band-pass : tapis pelewat pita
Filter-high-pass : tapis pelewat-tinggi
Filter-low-pass : tapis pelewat-rendah
Finite : anta, terhingga
Flat : rata
Flip-flop : kalak-kalik
Floating point : titik ambang
Floppy disk : disket liuk
Flourescence : pendarflour
Flow chart : bagan air
Flow diagram : diagram alir
Fluctuation : ginjatan
Fluid : zalir, fluida
Focus : pumpun, fokus
Force : kakas, forsa
Forecast : prakiraan
Forward pass : laluan maju
Four-terminal network : jaringan empat titik
Fraction : pecahan
Frame : kerangka
Frequency : frekuensi
Full coding : penyandian penuh
Fundamental circuit : sirkuit dasar
Fuse : sekring

G
Gap test : uji celah
Gain : bati, penguatan
Gate : gerbang
General agent : agen umum
Generalize : merampat
Generator : pembangkit, generator
Glide reflection : pencerminan luncur
Global error : galat error
Global error estimation : dugaan galat global
Global maximum : maksimum global
Global property : sifat global
Glow : pijar
Gradient : gradien, landai
Graph : graf
Grid : kisi

H
Half adder : penambahan setengah
Hard disc : disk keras
Hardware : perangkat keras
Hazard : bahaya
Heat : bahang
Hexadecimal code : sandi heksadesimal
Hexadecimal file : berkas heksadesimal
Hierarchy : hierarki
Host system : sistem induk
Horn : corong
Hot : panas
Humid : lengas
Hurwitz criterion : kriteria Hurwitz
Hybrid : bastar, hibrid
Hybrid computer : komputer hibrid

I
Idempotent : idempoten
Identical : seiras, identis
Identity : 1.keidentikan, 2.satuan
Idle time : waktu terbiar
If and only if : jika dan hanya jika
Image : santir, citra
Image processing : pengolahan citra
Imaginary : khayal, imajiner
Imbedding : benaman
Impact : dampak
Impedance : impedans
Improper Fraction : pecahan tak wajar
Include : tercakup
Inconsistent : tak konsisten
Increment : riap, inkremen
Inductioon : imbasan, induksi
Inertia : kelembaman, inersia
Infinite : ananta, tak hingga
Input : masukan
Insulation : sekatan
Interface : antarmuka
Invariant : karar, invarian
Invariance : kekararan
Inversion : inversi, pembalikan

J
Joint of ideals : sambungan ideal
Jumbo limit : limit risiko maksimum

K
K-flat : rataan-k
Kernel : kernel, bija
Keyboard : papan tombol
Keyword : kata kunci

L
Labile : goyah
Ladder : tangga
Lag : keter, beda kata
Lattice : kekisi
Lead time : masa tenggang
LED (Light Emitting Diode) : DPC (dioda pemancar cahaya)
Level : aras
Level curve : lengkung aras
Likelihood : kemungkinan
Limit : limit, batas
Limit element : unsur limit
Line : 1. Garis, 2. Baris
Linked blocks : blok terjalin
List : senarai
Load : beban
Loader : pemuat
Locus : lokus, tempat kedudukan
Logic : logik
Logic circuit : rangkaian logik
Logic design : rancangan logik
Loop : simpal, gelung
Loss : rugi
Loudness : kenyaringan
Lumped : terbungkal

M
Machine code : sandi mesin
Magnitude : magnitudo
Main column : kolom utama
Mantissa : mantis
Map : peta
Marker variable : peubah penanda
Master file : berkas induk
Matched : sepadan, berpadanan
Matching : pemadanan
Meager set : himpunan ramping
Mean : purata,pukul rata, nilai tengah
Mean range : purata kisaran
Mean square root : akar purata kuadrat
Mesurable : terukur
Median : median
Medium : zantara, medium
Megabyte : megabyte
Mesh : jaring
Microcomputer : mikrokomputer
Microprocessor : mikroprosesor, mikropengolah
Minimal cover : peliput minimum
Minimax characterization : perincian minimaks
Modification time : waktu modifikasi
Modified Euler formula : rumus Euler termodifikasi
Moment : momen
Momentum : pusa, momentum
Monitor system : sistem monitor
Monochrome : monokrom
Monostable : ekamantap, monostabil
Multibinomial test : uji multibinomial
Multiple Poisson distribution : swebaran Poisson ganda
Multiplication : perkalian
Multiplier : pengali
Multivariable calculus : kalkulus multipeubah, kalkulus peubah ganda
Multiwindow : multijendela

N
Nand gate : gerbang bukan-dan
Natural basis : basis alami
Negative semidefinite : semitentu negatif
Neighborhood : lingkungan, jiran
Nested design : rancangan tersarang
Net : jala, jaring
Network : jejala, jaringan
Neutral : netral
Neutral stability : kemantapan netral
Nodal point : titik simpul
Node : simpul
Noise : derau
Nonlinear : taklinear
Norm : norma
Normal : normal
Null : nol
Nullity : kenolan
Numerator : pembilang

O
Observable : teramati
Octal number system : sistem bilangan oktal
Odd : gasal, ganjil
Off-line : luar-talian
On-line : dalam-talian
One-sided test : uji satu arah
Open mapping : pemetaan buka
Operator : pengandar, operator
Operator method : metode operator
Optimal solution : penyelesaian optimum
Optimization : pengoptimumam
Optimum : optimum
Orbit : orbit edaran
Order : tingkat
Origin : 1.asal, 2.titik asal
Oscillation : ayunan, osilasi
Oscilllator : osilator, pengalun
Outcome : hasil
Output : keluaran
Output-device : piranti keluaran
Overdamped : lewat redam
Overflow : limpah atas
Overlap design : rancangan bertindih
Overshoot : lewat jelajah

P
Pair : pasangan
Parallel : sejajar, paralel
Parameter : parameter
Parity : paritas
Partial : parsial, panggu
Partitial : partisi, penyekatan
Password : sandi lewat
Path : lintasan
Pattern : pola
Payoff : langsaian, imbalan
Peak : puncak
Penalty cost : biaya pinalti
Pendulum : bandul
Pendulum motion equation : persamaan gerak bandul
Period : kala, periode
Periodic integrand : integran berkata
Permanent : daim, permanen
Permeability : ketelapan, permeabilitas
Pertubation : usikan
Pertubation technique : teknik usikan, tehnik pertubasi
Phase : fase
Piecewise continuous : kontinyuse sepenggal
Piecewise linearization : pelinearan sepenggal
Pivot column : kolom pangsi
Pixel : piksel
P.L.L (Phase Locked Loop) : simpul terkunci fase (STF)
Point : titik
Polar axis : sumbu kutub
Polar system : sistem kutub
Polynomial : suku banyak, polinomial
Positive semidefinite : semitentu positif
Power : daya
Predecessor : pendahulu
Predicate : predikat
Primary : ideal primer
Principal : modal dasar
Principle of duality : prinsip kedualan
Print menu : menu cetak
Printed circuit : rangkaian tercetak
Probability : probabilitas, kemantakan
Process control : kendali proses
Processor : pengolah prosesor
Product : darab hasil-kali
Production and employment : penjadwalan produksi dan pekerjaan
Scheduling : pekerjaan
Proof : bukti, pembuktian
Prapagation : rambatan
Proper : wajar
Property : sifat
Proposal : usul, proposal
Pseudobase : dasar menu
Pure death model : model kematian murni
Push : taruh
Puzzle : teka-teki

Q
Quadratic : kuadratik
Quasicompac cluster : gugus kuasikompak
Quasicompac function : fungsi kuasicekung
Queue : antrean
Quotient : hasil bagi, kuosien

R
Radiation : sinaran, radiasi
Radius : ruji, radius
Radix : bilangan pokok
Ramp : tanjak
Random : acak
Range : kisaran
Rank : peringkat
Ratio : nisbah
Ratio test : uni nisbah
Ray : sinar
Reactance : reaktans
Reaction : reaksi
Real axis : sumbu real
Record : rekord
Reciprocals : timbal-balik
Rectangular coordinate : koordinat siku
Rectifier : penyearah
Recurrence : perulangan, rekurents
Reduced echelon matrix : matriks eslon terduksi
Redudant equation : persamaan berlebihan
Reference : acuan
Reflector : pemantul
Regression : regresi
Regular : beraturan, regular
Regulator : pengatur
Relative : nisbi
Relative closure : ketertutupan nisbi
Relation : hubungan, relasi
Relaxation : pengenduran, relaksasi
Reliability : keterandalan
Remainder : sisa
Remote access : akses jauh
Reset key : tombol set kembali
Resistance : hambatan
Resistivity : keterhambatan
Resonance : talunan, resonans
Response : tanggapan, respons
Restart : mulai kembali
Resultant : resultan
Robotic : robotika
Robustness : kekerasan
Root : akar
Rotating tensor : tensor berputar
Rounding : pembulatan
Route : rute
Row : baris
Ruin theory : Teori kemusnahan

S
Saddle point : titik pelana
Safety margin : tepi kanan, batas kanan
Salvage cost : biaya, sisa
Sample : contoh, cuplikan
Saturated space : ruang jenuh
Saturation : jenuhan, sakurasi
Scalar : skalar
Scale : skala
Scanner : penyamar
Scatter diagram : diagram pencar
Scattering : hamburan
Schedule : jadwal, skedul
Semi conductor : semi penghantar
Score : skor
Screen display : tampilan layar
Search pattern : pola telusur
Seasonal index : indeks musiman
Secondary data : data sekunder
Segment : ruas, sekmen
Self-adjoint : adjoin, swa-adjoin
Semicircle : setengah lingkaran, semi lingkaran
Sensitivity analysis : analisis kepekaan
Sensitivity data : data kepekaan
Separable differential equation : persamaan diferensial terpisahkan
Separation of variable : pemisahan peubah
Sequence : barisan
Serial cluster : gugus serial
Series : deret
Set : waktu layanan
Shadow cost : biaya bayangan
Shadow price : harga bayangan
Shifting theorem : teorema geseran/ingsutan
Shock wave : gelombang kejut
Shot noise : derau tembakan
Side : sisi
Sign : tanda
Signal : isyarat, sinyal
Significance : nyata
Similar : sebangun, serupa
Simple circuit : sirkuit sederhana
Simplex : simpleks
Simply convergent filter : tapis konvergen sederhana
Simulation : simulasi
Simultaneous : simultan, serentak
Single linked block design : rancangan blok terjalin tunggal
Singular distribution : sebaran tunggal
Sink : muara
Sketch : sketsa
Skew correlation : korelasi pencong
Slack variable : peubah lempai
Slope : lereng, kelerengan
Smooth curve : lengkung mulus
Solenoidal vector : vektor selenoidal
Solid : zat padat
Solution : penyelesaian
Sorting method : metode pemilihan
Sorting procedure : prosedur pemilihan
Source : sumber
Source code : sandi sumber
Space : ruang
Special bar : batang spasi
Special projective coordinate : koordinaat projektif khusus
Specific rate : laju khas
Speed : laju, kelajuan
Spurious correlation : korelasi palsu
Square : 1.bujur sangkar, 2.kuadrat, 3.persegi
Square bracket : kurung siku
Square root : akar kuadrat, akar pangkat dua
Stability : kestabilan, kemantapan
Stable : stabil, mantap
Stable and attractive point : titik stabil dan tarikan
Stable solution : penyelesaian stabil
Stack pointer : penunjuk tumpukan
Staircase function : fungsi tangga
Standard : baku, standar
State : keadaan
Strain : regangan
Statics : statika
Statistic : statistik
Statistician : statiskawan
Steady state : keadaan tunak
Steering : pengarahan
Step function : fungsi tangga
Stochastic : stokastik
Stop list : senarai henti
Strategy : strategi, siasat
Stratum : lapisan
Steamline : garis arus
Stricly decreasing function : fungsi turun sempurna
Strips : jalur, pita
Strong root condition : syarat akar kuat
Structure : struktur
Subset : subbarisan
Subtractor : pengurang
Succeding number : bilangan berikut
Succeding approximation : hampiran berurutan
Successor : penerus
Sufficiency : kecukupan
Sum : jumlah
Summand : yang dijumlahkan, dijumlah
Summation : penjumlahan
Summit angle : sudut puncak
Super : adi, super
Supercompact space : ruang superkompak
Supercomputer : supercomputer
Superior : ataas superior
Supplement : suplemen-pelurus
Surface : permukaan
Surplus variable : peubah lebihan
Survey : survei, sigi
Susceptance : rentanan, suseptans
Syllable : suku kata
Symbols : lambang, simbol
Symmetric game : permainan simetrik
Symmetrization : simetrisasi, penyetangkupan
Symmetry : kesetangkupan
Synchronous : sinkron
Syntax error : galat sintaks
System analysis : analisis sistem
System call : panggil sistem
Systematic : sistematik
Sweep : sapuan, lejang
Stable : mantap, stabil

T
T-distribution : sebaran-T
T-score : skor-T
T-test : uji-T
T-1 space : ruang T1
Takacs process : proses Takacs
Tandem queue : berangkai, antrean tendem
Tangent : tangen, garis singgung
Tape : pita
Target language : bahasa sasaran
Term : 1.suku, 2.istilah
Temperature : suhu
Throughput : lewatan
Time lag : lama beda kala, keter waktu
Time sharing : patungan waktu
Tolerance distribution : sebaran toleransi
Tone : nada
Tool : alat
Toroid : toroid
Torsion : torsi
Trace of matrix : teras matriks
Trade-off function : fungsi tukar pilih
Transfer function : fungsi transfer
Transformation : alih ragam, transformasi
Transient : fana
Transient solution : penyelesaian fana
Transitive : transitif
Translation : translasi
Translation motion : gerak translasi
Transparency : kebeningan, transparansi
Transportation model : model pengangkutan, model transportasi
Transpose : tranpos
Trapezium : trapesium
Trapezoid : trapesoid
Travesal : melintang
Trial and error : coba-ralat
Trivial : trivial, remeh
True : benar
Truncated power series : deret kuasa penggal
Truncation : pemotongan, pemenggalan
Truth : kebenaran
Truth table : tabel kebenaran
Turnkey program : program siap-guna
Two sided test : uji dwiarah
Two's complement : komplemen dua
Type : tipe, jenis

U
U2 n test : uji U2 n
Unequal : taksama
Uniform convergence : kekonvergenen seragam
Unilateral component : komponen sepihak
Union : gabungan
Unique : tunggal, amung
Unit : satuan, unit
Univariate distribution : sebaran peubah tunggal
Universal affairmative : penegasan semesta
Unknown : anu
Upper bound : batas atas
Upper case : huruf besar
Utility function : fungsi manfaat, fungsi utilitas

V
Value : nilai
Variable : perubah, variabel
Variance : ragam,varians
Velocity : kecepatan
Vertical : vertikal, tegak
Vibrating membrane : selaput getar
Virtual work : satuan penampil visual
Voltage : tegangan
Volume : volume

W
Weight : bobot, berat
Width : lebar
Word : kata
Word Processor : pengolah kata

X
X-axis : sumbu-x
X-component : componen-x
X-coordinate : koordinat-x

Y
Yes or no decision : keputusan ya atau tidak
Yield rate : tingkat hasil

Z
Zone : daerah
Zero point : titik nol

Glossary - Banking (H)

2008-03-23T02:49:00.000-07:00

Hamburg Rules, peraturan Hamburg
Perangkat hukum pengangkutan yang terbentuk berdasarkan suatu konvensi internasional oleh UNCTAD yang mengatur tentang tanggung jawab pengangkut terhadap kerugian dan kehilangan dalam pengangkutan laut.

Hand Money, uang muka, panjar
Uang muka sebagai panjar atau tanda jadi suatu transaksi atau kontrak.
Lihat Earnest Money.

Handsel, jabat tangan tanda tercapainya kesepakatan
Istilah ini sering pula disamakan artinya dengan uang muka, sebab biasanya setelah jabat tangan diikuti dengan pembayaran uang muka.
Lihat Hand Money.

Harbor (n), pelabuhan laut

Harbor (v), memberi tempat, menampung
Memberi perlindungan atau tempat tinggal terhadap seseorang dengan maksud untuk menyembunyikannya.

Harbor Dues, biaya pelabuhan
Ongkos yang harus dibayar untuk menikmati pelayanan jasa ke pelabuhan.

Hard Cash, uang logam, koin
Mata uang dalam bentuk kepingan logam sebagai lawan dari uang kertas.

Hard Currency, mata uang keras
Segala alat tukar yang secara internasional dapat diterima yang tidak mendapat pengawasan penggunaannya oleh pemerintah dan tidak didukung oleh sistem nilai tukar atau kurs resmi.

Hard Loan, pinjaman keras
Pinjaman luar negeri yang pembayarannya harus dengan mata uang keras.

Hard money, uang ketat
Mata uang suatu negara yang memiliki nilai tukar stabil di dalam negeri maupun di pasaran luar negeri; mata uang dalam bentuk kepingan logam; situasi moneter suatu negara yang ditandai dengan tingkat suku bunga yang tinggi sehingga sulit bagi orang-orang untuk memperoleh pinjaman.
Lihat, HARD CASH.

Harmonized System, sistem harmonisasi
Sistem pengklasifikasian barang ke dalam nomor-nomor tarif tertentu yang diterima secara internasional.

Havana Charter, persetujuan Havana
Persetujuan internasional multilateral yang diadakan tahun 1948 di Havana bertujuan untuk membentuk suatu organisasi dagang internasional tetapi gagal, dan sebagai gantinya disahkannya persetujuan umum tentang tarif dan perdagangan atau GATT.

Hawker, pedagang kaki lima, pedagang asongan
orang-orang yang menjajakan barang tidak dengan membuka toko atau kios atau wa¬ning, melainkan dengan menawarkannya di tepi jalan; juga disebut sebagai pedagang sektor informal.

Hawking, berdngang di kaki lima, mengasong
Melakukan penjualan barang secara mengasong.

Hazard, azahar
Kondisi yang dapat menimbulkan bahaya.

Hearing, dengar pendapat, pemerikscuin
Proses atau tahap diskusi atau perundingan dalam membuat suatu undang-undang di parlemen; pemeriksaan perkara di depan hakim.

Heavy Market, pasar lesu
Keadaan bursa sekuritas yang lesu karena indeks harga sekuritas mengalami penurunan.

Hedge Clause, klausul pengingkaran
Klausul dalam suatu perjanjian yang menyatakan pengingkaran atau penyangkalan mengenai ketepatan informasi yang diperoleh dari sumber-sumber luar.

Hedger, pelaku tindakan cegah risiko
Seseorang yang tidak mau menanggung risiko dalam transaksi komoditi, valuta asing atau sekuritas, sehingga melakukan tindakan pencegahan risiko berupa pembuatan perjanjian lain berdasarkan spekulasi dengan maksud untuk mendapatkan kompensasi apabila benar terjadi fluktuasi harga di kemudian hari.

Hedging, cegah risiko
Menutup transaksi jual beli komoditi, sekuritas, atau valuta sejenis untuk menghindari kemungkinan kerugian karena perubahan harga.

Hidden Defect, cacat tersembunyi
Kerusakan atau cacat pada suatu benda yang tak tampak secara langsung atau yang sebelumnya tak diketahui terlebih dahulu, misalnya pembeli suatu barang tak mengetahui bahwa barang tersebut sesungguhnya mengandung kerusakan atau cacat sehingga ia bersedia membelinya, ternyata setelah kontrak terjadi ia baru mengetahui kerusakan tersebut.

High Finance, pembiayaan canggih
Penggunaan dana milik orang lain untuk tujuan spekulasi sehingga berisiko hilangnya atau rugiiiya si pemilik dana itu; meminjam atau meminta kredit dalam batas jumlah tertinggi yang diperbolehkan perundang-undangan; jenis transaksi keuangan atau pembiayaan yang sangat rumit.

High Seas, laut bebas
Bagian tertentu dari wilayah lautan di luar batas wilayah perairan nasional suatu negara.

Hire (v), menyewa
Perbuatan hukum berupa mempekerjakan seseorang dengan suatu pembayaran sejumlah uang, memakai atau menggunakan sesuatu barang dengan membayar sejumlah uang.

Hire Purchase, sewa beli
Perjanjian sewa dengan hak opsi untuk membeli barang yang disewa; pembelian barang dengan pembayaran angsuran dalam hal hak milik atas barang tersebut baru beralih secara sah ke pihak pembeli setelah ia membayar angsuran terakhir.

Hirer, penyewa
Orang yang menyewa suatu barang dan atau jasa.

Hold (v), memegang
Menguasai sesuatu benda atau hak dengan alas hak yang sah.

Holder, pemegang
orang yang menguasai atau memegang suatu hak, atau benda.

Holder in Due Course, pemegang sah
Seseorang yang secara hukum berwenang untuk memegang suatu hak atas benda bergerak atau benda tetap secara sah.

Holder in Good Faith, pemegang yang beritikad baik
Pemegang suatu alas hak yang jujur, tak bermaksud buruk yang harus mendapatkan perlindungan hukum.
Lihat Good Faith Purchaser.

Holding Company, perusahaan atasan
Perusahaan yang tidak menjalankan kegiatan bisnis sendiri melainkan mengendalikan perusahaan-perusahaan lain dengan cara memiliki sebagian atau seluruh saham dari perusahaan-perusahaan tersebut.

Home Banking, bank rumah
Konsep perbankan modern di mana seorang nasabah dapat menghubungi banknya untuk meminta segala informasi yang menyangkut rekeningnya serta melakukan berbagai transaksi cukup dengan meng¬gunakan pesawat telepon.

Home Country, negara asal investor
Negara tempat domisili hukum perusahaan-perusahaan asing atau investor asing yang melakukan transaksi bisnis ke luar negeri.

Home Financing, pembiayaan perumahan
Jenis kredit berjaminan yang diberikan kepada nasabah untuk keperluan pembelian dan atau pembangunan rumah.

Home Improvement Loan, pinjaman perbaikan rumah
Jenis kredit perbankan berjangka pendek dengan atau tanpa jaminan berupa hak tanggungan, yang dipemntukkan bagi nasabah yang bermaksud untuk memperbaiki, merawat atau memperluas rumahnya.

Home Port, domisili kapal
Tempat kedudukan hukum suatu kapal adalah pelabuhan di tempat kapal tersebut didaftarkan, atau pelabuhan terdekat dengan domisili pemiliknya.

Home Port Doctrine, ajaran domisili kapal
Kapal-kapal samudera yang menjalani pelayaran antamegara hanya akan dikenai pajak di dan menurut hukum tempat domisili kapal itu.

Honor (v), mengaksep, membayar
Mengaksep suatu wesel atau membayar suatu surat utang.

Honorarium, honorarium
Suatu pembayaran tanda hormat atau terima kasih terhadap seseorang atas jasanya.

Horizontal Merger, merger horisontal
Penggabungan beberapa perusahaan yang memproduksi produk yang sama atau sejenis dan menjualnya di wilayah pemasaran yang sama.

Horizontal Price Fixing Contracts, kontrak penetapan hnrga horisontal
Perjanjian penetapan harga antara sesama produsen produk sejenis atau produk identik, antara sesama distributor atau antara sesama pengecer.

Host Country, negara tuan rumah investor
Negara tempat aktivitas investor asing dan perusahaan asing melalui perusahaan nasional yang berafiliasi dengan induknya berlangsung.

Hot Card, kartu panas
Istilah untuk menggambarkan pemakaian kartu kredit melebihi batas maksimum kredit yang diberikan, umumnya peristiwa ini terjadi bila kartu kredit tersebut hasil curian, sehingga si pencuri menggunakannya secara tak sah dengan maksud menguras rekening pemilik asli dari kartu kredit itu.

Hot Card List, daftar kartu panas
Suatu daftar yang dimiliki pihak bank penerbit kartu kredit yang berisi identitas kartu-kartu yang hilang dan atau di curi beserta nomor rekening dan identitas pemiliknya yang sah.

Hot Money, uang panas
Uang yang secara cepat dilarikan atau dipertaruhkan untuk sasaran tertentu karena suatu perubahan kecil pada harga dengan tujuan memanfaatkan kesempatan untuk mencari keuntungan.

House Brand, lambang dagang pribadi
Lambang dagang yang dipakai oleh pedagang besar bukan produsen untuk barang yang dibelinya dari produsen tanpa lambang dagang.

Hybrid Security, sekuritas campuran
Suatu jenis sekuritas yang mengandung dua unsur sekaligus yaitu unsur pengakuan utang dan saham.

Hyperinflation, hiperinflasi
Inflasi yang melaju sangat cepat dan tinggi.

Hypotheca, hipotik
suatu hak kebendaan atas benda-benda tidak bergerak untuk mengambil penggantian daripadanya bagi pelunasan suatu perikatan (pasal 1162 KUHPerdata).

Hypothecate, pembebanan hak tanggungan, pemasangan hipotik
Perbuatan hukum berupa pembebanan hak tanggungan atau hipotik atas benda tetap, yang meliputi tahap pembuatan akta pemberian hak tanggungan dan tahap pendaftarannya di kantor pertanahan.

Hypothecation of Securities, agunan sekuritas
Penyediaan sekuritas untuk agunan pinjaman bank.

Hyphotheque, hipotik, hak tanggungan
Hak jaminan yang dibebankan pada hak atas tanah berikut atau tidak berikut benda-benda lain yang merupakan satu kesatuan dengan tanah itu, untuk pelunasan utang tertentu, yang memberikan kedudukan yang diutamakan kepada kreditur tertentu terhadap kreditur-kreditur lain.
Lihat Hyphoteca.