Earth Sciences 1022A/B Lecture 8: L8 Geological time part 1
27 Apr 2019
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Document Summary
The overwhelming majority of earth"s history is recorded in rocks. Written human history extends back about 5,000 years. (pshah) Geologic materials record 4,600,000,000 years of earth history. Knowing how specific rocks are formed is great (what we"ve learned so far), but rocks are even more useful when we can interpret: 2, the implications of their formation in the context of earth as a whole. Two concepts of time are used in geology: Relative time: based on the sequential timing of geological events (i. e. the order in which events occurred; a before b). Absolute time: the determination of age in years before present, based on the decay of radioactive isotopes. All events occur in a sequence, regardless of their duration or specific time of occurrence. e. g. , typically breakfast, before lunch, before dinner. In relative time, we view geologic events in terms of their relative age (did something occur before or after another event?)
