30.2 THE PRECAMBRIAN AND PALEOZOIC
Jan 02, 2016
30.2 THE PRECAMBRIAN AND PALEOZOIC
PRECAMBRIAN TIME
Not an official part of the geologic time scale, more a reference for the Archean (~3.9 bya-2bya) and Proterozoic eons (lasted 2b.y.). Most of Earth’s history.
PRECAMBRIAN TIME
Evidence from Precambrian time periods
Cratons – the remains of Precambrian mountains and highlands. Located in shields (exposed cratons).
The oregnies that produce the Precambrian cratons.
Stromatolites: mats of trapped sediments and cyanobateria that formed layered domes.
PALEOZOIC ERA
Includes six periods Cambrian Ordovician Silurian Devonian Carboniferous Permian
PALEOZOIC ERA
Cambrian Period Most common
fossil is the trilobite. Ocean bound.
Warm oceans covered most of what is N. America
120 animal types have been found.
Photosynthetic algae
PALEOZOIC ERA
Ordovician Period Graptolite invertebrates. (tiny, lived in colonies) Also lived in oceans Japan collide w/ N. America causing mountains in
eastern part of US. Photosynthetic algae
PALEOZOIC ERA
Silurian Period The appearance
of land animals Appearance of
land plants Shallow seas in
N. America evaporated leaving a salt belt from New York to Lake Michigan.
PALEOZOIC ERA
Devonian Period Age of fishes
(jawless and jawed) Lungfish fossils
(can come out of water)
First forest Scaly bark trees
Arcadian Orogeny (mountains from Newfoundland to Appalachians)
PALEOZOIC ERA
Carboniferous Period (Mississippian/Pennsylvanian Periods)
Crinoids and Foraminifera (invertebrates during the Mississippian period)
Appearance of reptiles and true land vertebrates
Left huge coal deposits in the US
PALEOZOIC ERA
Permian Period Dry climate Pangea Sponges, corals and
algae Permian Extinction (251
mya) 96% of all marine ssp/ 70-
80% of land animals Climate
change/Catastrophe or Increased volcanism believed to be cause.