ESS105H1 Chapter Notes - Chapter 5: Phanerozoic, Geologic Time Scale, Mesozoic
Document Summary
James hutton: realised that processes were acting on the planet that weren"t perceivable to humans because they acted so slowly; observed this from the juxtaposition of horizontal and vertical rocks. Stratigraphy: study of stratified (layered) rocks and their age relationships. Principle of superposition younger sedimentary rocks lie on top of older rocks. Principle of original horizonality: sedimentary strata are deposited initially as horizontal layers. Radiometric dates provide age of rocks and fossils and approximate rates of processes. Radiometric dates are derived from radioactive decay (using half-life concept and ratio of parent to daughter) Principle of cross cutting relationships: states that rock bodies that cut across others must have come after them. William smith proposed the principle of faunal succession fossil assemblages always occurred in the same superpositional sequence. Precambrian records the origin and development of earth in its three eons; hadean, Archean, and proterozoic; each eon has distinctive rock types and climates.
