GEOL 104 Final: Geology Exam Review 2012
17 Aug 2013
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Absolute time is the age of a geologic feature or event in terms of years (or millions of years) Relative time is the age of a geologic feature in terms of being older or younger than something else. Fundamental principles of relative time: law of original horizontality. Sedimentary units were originally deposited in horizontal layers parallel to the earth"s surface. Folded or tilted beds have been disturbed after deposition: law of superposition. In a sequence of sedimentary strata (or extrusive igneous rocks) that has not been overturned, the oldest layer is at the bottom. Older beds above younger indicate the beds have been overturned: james hutton (1785) - uniformitarianism = present is the key to the past. Recognized great gaps in the geologic record by examining cycles of erosion, deposition, erosion etc. which required extensive time. William smith (early 1800)created the first geologic map using fossils of.
