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.