Geology Quiz 2 Review - Names of geologic periods of the...

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Names of geologic periods of the Paleozoic, Mesozoic, and Cenozoic Eras (fig. 13-13, pg. 237) Division of time is called a geologic period o Rocks deposited during this period comprise a geologic system Ex. strata of the Cambrian System were laid down during the Cambrian Period Eon > Era > Period > Epoch Phanerozoic Eon o Cenozoic Era (most recent) Quaternary Pleistocene Tertiary Pliocene Miocene Oligocene Eocene Paleocene o Mesozoic Era Cretaceous Jurassic Triassic o Paleozoic Era Permian Pennsylvanian Mississippian Devonian Silurian Ordovician Cambrian Era: C _ M _ __ _P ____ Period: Q T _ CJT _ PPMDSOC Epoch: P_ PMOEP Pg. 277? 8 Lectures organic evolution, early life, making fossils, earliest metazoans principles of stratigraphy, geologic time scale geologic history of vertebrates earthquakes, seismic waves locating earthquake epicenters, earth’s deep interior gravity, mountain-making earth magnetism depositional systems I: streams
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LECTURE 10: EARLY ATMOSPHERE, EARLIEST ANIMAL LIFE, MODES OF FOSSILIZATION If the earliest atmosphere was of volcanic origin, it must not have contained oxygen gas (O2), which is not emitted from volcanoes . Thus, the earliest organisms must have been anaerobic (able to live in the absence of free oxygen). Photosynthesizers emplaced oxygen, a by-product of photosynthesis, into the atmosphere. Only after a substantial buildup of O2 had occurred was it possible for animals, which are aerobic organisms , to exist. At first, the oxygen promptly combined with dissolved iron ions , causing hematite (Fe2O3) or magnetite (Fe3O4) to precipitate. Ferrous iron (Fe+2) dissolves in water, whereas compounds that contain ferric iron (Fe+3), including minerals consisting of iron oxide (hematite and magnetite), are generally highly insoluble . This iron of sedimentary origin forms the world's greatest iron ore deposits. Only much later (perhaps at the Precambrian-Cambrian transition?) did oxygen begin to accumulate significantly in the atmosphere. Multiple-celled organisms (all of them eukaryotes) appeared in the fossil record nearly two billion years after the early prokaryotes. There is a fossil record of animals, known as the Ediacara fauna that lived during latest Precambrian time . Many of these soft-bodied creatures had a very large surface area compared to body volume, and a number of them had body plans that are totally unknown today. For example, the body of one animal consisted of inflatable interconnected compartments like an air mattress. Lacking jaws and teeth, these animals were passive feeders . They could not be predators, but rather, they waited for food to be wafted to them. (Ediacara fauna immediately predate the explosion of life-forms at the beginning of the Cambrian Period)
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This note was uploaded on 02/25/2011 for the course GEO 303 taught by Professor Leon during the Spring '08 term at University of Texas at Austin.

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Geology Quiz 2 Review - Names of geologic periods of the...

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