CAS ES 351 Chapter Notes - Chapter 4: Faint Young Sun Paradox, Silicate Minerals, Clay Minerals
23 Mar 2019
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Sun was fainter earlier, but it continues to get brighter over the years. After the first half-billion years of earth, we get a record of climate from sedimentary rocks made up of particles that were eroded from other rocks, reworked by running water, and transported to a deposition site. Water-deposited sedimentary rocks are direct evidence that earth was not frozen for its first 3 billion years of existence. The first evidence of ice-deposited sediments occurs in rocs dated to 2. 3 billion years ago. Evidence of primitive life forms that date to 3. 5 billion years ago continue to tell us earth was too frozen or too hot back then. ~something must have been offsetting the suns weakness, and whatever that was, its not doing it today because then earth would be too hot for life. ~one solution is greenhouse gases if they were more abundant back thenso the reservoirs carbon was stored in could"ve changed throughout earth"s history.
