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4.1 & 4.2
Term | Definition |
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Uniformitarianism | a principle that geologic processes that occurred in the past can be explained by current geologic processes. |
Fossil | The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock. |
Trace fossil | a fossilized structure, such as a footprint or a coprolite, that formed in sedimentary rock by animal activity on or within soft sediment |
Climate | The weather conditions in an area over a long period of time. |
Ice core | a long cylinder of ice obtained from drilling through ice caps or ice sheets; used to study past climate. |
Bands | Some ice cores have regular layers, called bands, which form each year. Band size shows how much precipitation fell during a given time. |
Relative dating | and method of determining whether an event or object is older or younger than other events or objects. |
Superposition | a principle that states that younger rocks lie above older rocks if the layers have not been disturbed. |
Unconformity | a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time. |
Geologic column | an ordered arrangement of rock layers that is based on the relative ages of the rock and in which the oldest rocks are at the bottom. |