GEO 103 Lecture Notes - Lecture 9: Trace Fossil, Seafloor Spreading, Coprolite
17 Feb 2017
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Document Summary
Johannes walther (1860 - 1937) recognized that same facies found laterally also present in a vertical sequence. Holds that facies found in conformable (no breaks in record) vertical sequence also existed beside one another laterally. Walther"s law applies to marine transgressions and regressions. Extent, rates and cause of transgressions and regressions. During the phanerozoic, there were 6 major transgressions - regressions in north america. (the one transitioning between the permian e-l times. Rapid seafloor spreading, expands mid-ocean ridge system, displacing seawater onto continents. If the rate of seafloor spreading, on average the crust tends to be younger, warmer, which causes it to expand and then allows more water to fill in. Diminishing seafloor-spreading rates increases volume of ocean basins causing regression. There can be transgressions globally, but locally, there could also be regressions and vice versa. Using relative dating techniques, can determine the relative ages of rocks in columns a and b (textbook) over large distances.
