EXTRA CREDIT

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Stephen c

geologic time scale

The period of time covering the physical formation and development of Earth, especially the period prior to human history.

mid atlantic ridge

A submarine ridge system that extends the length of the Atlantic Ocean.  

fossils 1. The remains or impression of a prehistoric

organism preserved in petrified form or as a mold or cast in rock: "sites rich in fossils"; "the buildings are still intact, fossils of another culture"; "a fossil fish".

Absolute Age Absolute dating is the process of determining

a specific date for an archaeological or palaeontological site or artifact.

Relative age The age of a rock or an event as compared with

some other rock or event..

law of superposition Superposition is the principle that states that,

in undisturbed strata, newer layers will be deposited over older layers; thus, in a core sample, those samples of earth and rock nearest the surface will be newer in age than those beneath them.

Unconformity 1. A surface of contact between two groups of

unconformable strata.

Extinct no longer in existence; that has ended or died

out: an extinct species of fish.

index fossil a widely distributed fossil, of narrow range in

time, regarded as characteristic of a given geological formation, used especially in determining the age of related formations.

Extinction the fact or condition of being extinguished or

extinct.

mass extinction An extinction event (also known as: mass extinction;

extinction-level event, ELE, or biotic crisis) is a sharp decrease in the diversity and abundance of macroscopic life. They occur when the rate of extinction increases with respect to the rate of speciation

Pangaea A vast continental area or supercontinent

comprising all the continental crust of the earth, postulated to have existed in late Paleozoic and Mesozoic times before breaking up into Gondwana and Laurasia.  More »

evolution 1. The process by which different kinds of living

organisms are thought to have developed and diversified from earlier forms during the history of the earth.

magma Noun: Hot fluid or semifluid material below or

within the earth's crust from which lava and other igneous rock is formed by cooling.  

Lithosphere the solid portion of the earth ( distinguished

from atmosphere, hydrosphere).

natural selection Noun: The process whereby organisms better

adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.  More »

adaptations 1. The action or process of adapting or being

adapted.

Continental Drift Noun: The gradual movement of the continents

across the earth's surface through geological time.  More »

theory of plate tectonics Plate tectonics (from the Late Latin tectonicus,

from the τεκτονικός "pertaining to building") is a scientific theory which describes the large scale motions of Earth's lithosphere.

asthenosphere Noun: The upper layer of the earth's mantle, below

the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.  More »

convergent boundary In plate tectonics, a convergent boundary also

known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of lithosphere move toward one another and collide. ....  More »

Divergent boundary In plate tectonics, a Divergent boundary or

divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. ....  More »

Transform boundary A transform fault or transform boundary, also known

as conservative plate boundary, is a fault which runs along the boundary of a tectonic plate. The relative motion of such plates is horizontal in either sinistral or dextral direction. ....  More »

Subduction Noun: The sideways and downward movement of

the edge of a plate of the earth's crust into the mantle beneath another plate.  More »

Volcano Noun: A mountain or hill, typically conical, having

a crater or vent through which lava, rock fragments, hot vapor, and gas are or have been erupted from the earth's crust.  More »

Lava Noun: Hot molten or semifluid rock erupted from a

volcano or fissure, or solid rock resulting from cooling of this.  

Earthquake A sudden and violent shaking of the ground,

sometimes causing great destruction, as a result of movements within the earth's crust or volcanic action

Fault Noun: An unattractive or unsatisfactory feature,

esp. in a piece of work or in a person's character.  More »

hot spot 1. A small area or region with a relatively hot

temperature in comparison to its surroundings.

mechanical weathering Weathering is the breaking down of Earth's rocks,

soils and minerals through direct contact with the planet's atmosphere. ....  More »