ESCI 1001 Lecture Notes - Lecture 10: Geologic Time Scale, Nonconformist, Uniformitarianism
Document Summary
Uniformitarianism present is the key to the past . Superposition younger rocks are deposited on top of older rocks. Original horizontality rock layers are deposited horizontally/parallel to earth"s surface. Nonflat layers means there was folding or tilting. Lateral continuity rock layers extend in all directions until the edge of their area appears on both sides of canyon. Cross-cutting relationships igneous intrusion (ex: dike) or a fault that crosscuts rock layers, is younger than the rock layers it crosscuts. Inclusions inclusions/rock fragments are older than the rock they are within. Unconformities layers within the earth that represent periods of erosion/no deposition gap in geologic time. Angular unconformities horizontal layers are deposited on tilted/folded layers. Nonconformity sedimentary layers deposited on top of igneous/metamorphic. Disconformity sedimentary layers on top of sed. Eons longest time range (archean, protorozok, phanerotoic) Eras defined by mass extinctions (short interval where many species went extinct.
