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Phanerozoin Eon means:
"visible life"
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Phanerozoic Eon occured:
542 million years ago to the present
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Phanerozoin Eon consists of 3 eras:
- - Paleozoic "ancient life
- - Mesozoin "middle life"
- - Cenozoic "recent life"
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The Paleozoic Era can be divided into 2 parts:
Early Paleozoic and Late Paleozoic
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Cambrian, Ordovician, and Silurian
Early Paleozoic
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Devonian, Mississippian, Pennsylvanian, and Permian
Late Paleozoic
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Vascular plants on land first appeared in...
late Silurian; erosion was active/severe without plant roots to hold soil
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The first-occurance of shell-bearing organisms:
the base of the Cambrian; trilobites, brachiopods, molluscs
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The oldest occurance of feeding burrows of the trace fossil Phycodes pedum
the base of the Cambrian
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The Paleozoic is characterized by long periods of sedimentations punctuated by mountain building
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Paleoclimatic evidence comes from environmentally-sensitive sedimentary rocks
glacial depisots, coal swamp deposits, reef carbonates, evaporites
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The early Paleozoic climate was affected by:
- - Earth spun faster & had shorter days
- - tidal effects stronger because Moon was closer to Earth
- - vascular plants were absent on land
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Major Orogenic Belts:
- - Appalacian Mtns
- - Ouachita Mtns
- - Cordillera Mtns
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Paleozoic rocks of the platform are:
relatively flat-lying to gently dipping (warped into basins, doms, arches, synclines)
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Paleozoic rocks in Ouachita-Appalachian orogenic belt are:
severely deformed (folded, faulted, etc)
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mountain-building events
orogenies
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In Appalachian region, there were 3 Paleozoic orogenies:
- - Taconic orogeny (Ordovician)
- - Acadian orogeny (Silurian-Devonian)
- - Alleghanian orogeny (Pennsylvanian)
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When did the supercontinent Rodinia rifted apart to form several large continents?
just before the Paleozoic
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When continents are located on a pole, glaciers will form
shallow epicontinental seas are unlikely during glaciations
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By Cambrian period, continents moved off the pole
some continents lie on the equator
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By Cambrian Period, glaciers melted and sea levels rose
shallow epicontinental seas flooded the continents
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Laurentian
North American
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During the Early Paleozoic, shallow epicontinental seas transgressed across Laurentian (N. American) craton
this happened as the glaciers melted and sea level rose
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seas regressed as the glaciers enlarged and sea level dropped
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Epicontinental Seas (during transgression)
sands, muds, and carbonates were deposited in the shallow seas
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Cambrian Paleogeography of N. America
Laurentia is covered in shallow seas; lies on equator so water is warm; water deeps towards edges of continent where shale is deposited
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planktonic (floating) colonial animals; fossils occur as black marking in dark shale
Graptolites
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Taconic Orogenic Belt
lies between Laurentia (N. America) and Baltica (Europe) in Ordovician; partial closer of lapetus Ocean
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As Taconic mountain belt eroded,
huge delta systems spread westward
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During Ordovician, Gondwana moved towards S. Pole
leading to glaciation in Africa at end of Ordovician
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End of Ordovician:
sea levels dropped sharply; glaciation
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In the Middle ____, shallow seas covered more of the continents than at any other time
Silurian
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The epicontinental seas withdrew toward end of the:
Silurian
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