EESA06H3 Lecture 6: Lecture 6 In Class Notes
29 Apr 2011
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Hadean was the first time on earth, nicknamed hell on earth , beacuase the rocks were molten, no ocean, no atmosphere. But then the world differentiated, heavy elements sank down becoming the core, mantle, crust, etc. This also allowed a magnetic field to be developed, which created the conditions to build an atmosphere by constricting the gases and oceans. Four major steps to life on earth: the earliest bacteria 3. 8 ga, the cambrian explosion 542 ma (multicellular organisms with shells, backbones, etc. , diversification during the paleozoic c. 400-240ma, role of meteorites. A fossil is formed by any cavities filled in with silica, calcium carbonate, iron a process called mineralization. Ammonite fossils: have identical halves; iridescent aragonite with trace elements (fe, Trace fossils are preserved tracks, trails, burrows, borings. Palaeoecology: study of ancient organisms and their environment. Clues of the ancient environments can be from: fossil types, assemblages (groups of fossils usually found together), fossil morphology (shape), trace fossils.
