ERS120H5 Lecture Notes - Lecture 17: Stromatolite, Proterozoic, Archean
Document Summary
Plantetesimals hrow into the proto-earth on accretion, which results from the accumulation of particles and gases into a larger accretionary disk. Individual smaller particles get bound together and grow into an earth. Soon after earth forms, a small planet collides. The moon forms from the ring of debris. Before we had magma oceans and a closer moon. Got hit by various comets and asteroids. We had plate tectonics in a completely different way. Some plates are 3. 5 billion years old. Stromatolites cyanobacteria that use up co2 and releasing o2. Around the proterozoic time, a great amount of oxygen has accumulated in the air. There are glacier rocks spread all around continents. Breakup of supercontinent rodinia = small continents near the equator. Formerly landlocked areas are closer to ocean moisture = more erosion. Oceans freeze ice to average depth of more than 1 km. Volcanoes emit co2, which builds back up in the atmosphere.
