EARTHSS 1 Chapter Notes - Chapter 7: Radiometric Dating, Cross-Bedding, Hadean
24 Oct 2018
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Document Summary
Relative age - age in comparision to another material. Numerical age - actual time when a specific event happened or a specfic material formed or was deposited. Radioactivity was the first way to measure numerical age - radioactive decay = same time, same speed - we measure by radiometric dating. Geologists assembed the geloic column that shows the chronological order of the succession of rock units: Usualy boundaries between units signify major geologic events like mass extinctions. Depositiion of sediment makes dsitinct layers - sedimentary bedding-stratification - each layer is a stratum. Principle of original horizontally - sedimentary is deposited in a horizontal layer, r parallel to the earths surface, if its ot horizontal its prob because its been broken down or disturven by tectonic forces. Principle of stratifraphic superposition - oldest strata is on the bottom, newer on top.
