ISCI 1A24 Lecture Notes - Lecture 3: Geologic Time Scale, Nonconformist
29 Sep 2016
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Document Summary
How to which rocks are older/younger in a sedimentary succession: Principle of original horizontality beds of sediment laid down in water form horizontal or near-horizontal layers. Principle of cross-cutting relationships a geological feature that cuts across or penetrates another body must be younger than the rock mass penetrated. Principle of inclusions fragments included in the host rock are older than the host rocks. How can we match the age of rocks form one area to another? correlation determining time equivalency of rock units; similarity in lithology and/or fossils. Principle of faunal successions fossil species succeed one another in recognizable order; index fossils (commonly found, easily identified) relate to specific time periods unconformity gap in geological record. Disconformity layers above and below the unconformity are parallel to one another. Angular conformity younger beds overlie tilted or folded beds.
