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earths history

index fossils a fossil that is useful for dating and correlating the strata in which it is found.
lithosphere the rigid outer part of the earth, consisting of the crust and upper mantle.
extinction no longer in existence
law of superposition a basic law of geochronology, stating that in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom, each layer being younger than the one beneath it and older than the one above it.
unconformities a surface of contact between two groups of unconformable strata.
divergent tending to be different or develop in different directions
convergent coming closer together, especially in characteristics or ideas
transform make a thorough or dramatic change in the form, appearance, or character of.
faults an unattractive or unsatisfactory feature, especially in a piece of work or in a person's character.
plate tectonics a theory explaining the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithospheric plates that move slowly over the underlying mantle.
Continental drift the gradual movement of the continents across the earth's surface through geological time.
absolute age an age on a specified chronology in archaeology and geology.
relative age determining the relative order of past events
half-life the time taken for the radioactivity of a specified isotope to fall to half its original value.