GRS IR 701 Lecture Notes - Lecture 2: East African Rift, Flor, Supercontinent Cycle
9 Nov 2017
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Document Summary
The radioactive fuel of earth is: u, th, and k. Relative to the age of the earth, the fraction of time that human-like species have existed is: 0. 04% Early heating of the earth: formed the core and mantle, melted some iron and nickel that sank to form the core, led to the formation of the magnetic field, and occurred shortly after planetary formation. Early life on earth began in the oceans, dates back to 3. 8 billion years, was of one-celled bacteria and algae, and thrived near sea floor plate boundaries. The cretaceous-tertiary extinction was caused by asteroid impact, led to the end of the. Age of reptiles, led to the beginning of the age of mammals, and occurred at 66 million years ago. Humans on earth: as the genus home date back to 2. 5 million years and the species, Homo sapien, 200,000 years. , did not have a population of about 1 billion until the year.
