Beginning of the Proterozoic marks the beginning of:
More modern style of plate tectonics & sedimentation; More modern global climate w/ glaciations; Establishment of beginnings of oxygen-rich atmosphere; Emergence of eukaryotes
Major events of the Paleoproterozoic:
Active plate tectonics & mountain building; Earth's first glaciation; Rise in atmospheric oxygen; Accumulation of high concentrations of organic matter in sediments
Evidence for glaciation includes: Varves
mudstones w/ alternating summer and winter layers of sediment
Evidence for glaciation includes: Glacial dropstones
Dropped from melting icebergs in varved sedimentary rocks
Evidence for glaciation includes: Striation on beds
due to abrasion as ice moved
Extensive banded iron formations on the western shores of Lake Superior indicated that:
photosynthesis was occurring and oxygen was being produced
Highlights of the Mesoproterozoic (1.6 to 1 billion years)
Assembly of supercontinent Rodinia (1.1 billion years ago)
Rifting in Rodinia:
Began to rift and break up about 750 million years ago– forming the proto-Pacific Ocean