CAS BI 107 Chapter Notes - Chapter 25: Extinction Event, Carboniferous, Half-Life
15 Oct 2016
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Document Summary
Nicolaus steno realized that undisturbed sedimentary rocks (rocks formed by accumulation of sediments), the oldest layers of rock (strata) lie at the bottom and the successively higher strata are progressively younger. The decay of radioactive isotope into stable isotopes happens at a steady rate. A half-life is the time it takes for half of the remaining atoms to decay in this way. Different radioisotopes have different characteristic half-lives that allow us to estimate the age of rocks. Radiometric dating of rocks over 60,000 years require estimating radioisotope concentrations in igneous rock, which is formed when molten lava cools. Paleomagnetic dating relates the age of the rocks to patterns in earth"s magnetism, which changes over time (used when sedimentary rock does not contain suitable igneous intrusions and few fossils are present) Physical changes in earth influences evolution of life and life has influenced. Phanerozoic eon has been notable for rapid diversification of multicellular eukaryotes.
