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Physics, Astronomy & Cosmology / Why did Amplifier Lakes in the Rift Valley only undergo cycles every 800K years?
« on: 05/10/2020 21:23:09 »
Hey everyone. I know this might not immediately seem like a question for this section, but it's actually based in Astronomy.
I'm currently reading Origins by Lewis Dartnell. According to the book, there are lakes in East Africa where humanity evolved that were called Amplifier Lakes and every 800K years would undergo quick cycles of filling and draining that helped to drive human evolution. During maximum eccentricity (when the Earth's orbit is most elongated), changes in the precession cycle (the wobble of the earth's axis), would cause the lakes to undergo the cycles. But, the eccentricity cycle is 100K years and the precession cycle is 26K years. So, I'm wondering why this phenomenon only occurred every 800K years. Why didn't it occur every 100K years?
I'm guessing it's the result of some complicated interplay between the precession cycle needing to be at a certain point during maximum eccentricity, but I would appreciate any elucidation on this. Thank you.
I'm currently reading Origins by Lewis Dartnell. According to the book, there are lakes in East Africa where humanity evolved that were called Amplifier Lakes and every 800K years would undergo quick cycles of filling and draining that helped to drive human evolution. During maximum eccentricity (when the Earth's orbit is most elongated), changes in the precession cycle (the wobble of the earth's axis), would cause the lakes to undergo the cycles. But, the eccentricity cycle is 100K years and the precession cycle is 26K years. So, I'm wondering why this phenomenon only occurred every 800K years. Why didn't it occur every 100K years?
I'm guessing it's the result of some complicated interplay between the precession cycle needing to be at a certain point during maximum eccentricity, but I would appreciate any elucidation on this. Thank you.