GLGY 209 Lecture 16: Glaciers Lecture part 2
15 Apr 2016
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Document Summary
Much of north american terrain was covered by ice. The period of ice age started about 2 and a half million years ago. A beter record of iming is scene in at the botom of the sea, where you can see temperature, and isotopes. In an observaional sense, the earth"s orbit changes. This change is known as the milankovitch cycle. The advance and retreat of the ice corresponds to the earths ilt. These changes come with a 41, thousand year periodicity. There was a ime when the earth"s orbit drew farther from the sun then returned closer to the sun. Over ive million years of climate change, ice remains throughout a large ime. The reason for the glacial change isn"t known. The sun has spots on it, that come and go on an 11 year cycle. (there is something going on with the sun)
