GEOL 1020 Lecture Notes - Lecture 2: Geologic Time Scale, Coal Measures, River Wear
7 Dec 2017
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Realized importance of fossils as indicators of time. Biostratigraphy: organization of strata (layers of rocks) based upon their fossil content. Boundary between permian-aged yellow sands formation the. Carboniferous-aged pennine upper coal measures exposed along the banks of the. Each rock unit had a distinct assemblage of fossils. These same fossil assemblages could be recognized at other places. Fossil assemblages occurred in the same sequence (or order) at different places. Principle of faunal (or fossil) succession: fossil assemblages succeed one another through time in a regular, predictable order. Smith"s (1816) strata identified by organized fossils, a guide to identifying. Principle of superposition: in an undisturbed sequence of strata, the oldest layer is on the bottom and youngest at the top. Principle of original horizontality: layers are initially deposited horizontally and any deformation must have occurred after deposition. Principle of lateral continuity: strata are originally unbroken flat expanses, but this lateral continuity can be broken by a river.
