GEO 103 Lecture Notes - Lecture 10: Radiometric Dating, Brachiopod, Biozone
22 Feb 2017
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Document Summary
Time-stratigraphic or chronostratigraphic units, consists of rocks deposited during a particular interval of geologic time. Time or geochronologic units designate certain parts of geologic time. Basic unit of time is the period (corresponds to system) 2 or more periods may be designated era. Periods can be subdivided into epochs, which in turn can be subdivided into ages. Silurian rocks are deposited in a silurian system of time. Lithostratigraphic units (rocks only and not equal since rocks can cut across time) Correlation is process of matching up rocks in different areas. Lithostratigraphic correlation matches up with same rock units over large area with no regard for time. Correlation of lithostratigraphic units such as formations traces rocks laterally across gaps. There can be pinch-outs and intertonging relations between two rock layers hundreds of kilometers apart that could add to the complexity to the matching. Matching in the layers hint at very similar deposition processes and time.
