Earth Sciences 1022A/B Lecture Notes - Lecture 9: Ordovician, Paleozoic, Mesozoic

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 1022A/B
• Professor: Cam Tsujita

Document Summary

Relative time= based on the relative timing of geologic events (the order in which events occurred) Absolute time= the determination of age in years before present, based on the decay of radioactive isotopes. All events occur in sequence (regardless of duration or speci c time) If not horizontal, they have been squished by tectonic forces. States that sedimentary strata are deposited in continuous sheets. Can be in separate areas (due to eroding) States that in any sequence of layered rocks, older rocks are below newer rocks. States that a fault (crack) must be younger than the rock through which it cut. States that fossils occur in consistent vertical order in sedimentary rock. Rate of sediment deposition is not uniform through time. Pauses in sediment deposition can occur, or rock removed by erosion (time goes. Unconformities= surfaces representing these slices of missing time. Disconformity= surface overlain or underlain by strata parallel to that surface.