BIO120H1 Chapter Notes - Chapter 2: Pope Pius Xi, Radiometric Dating, Igneous Rock
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BIO120H1 Full Course Notes
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Document Summary
The earth"s crust is a history book with the story of life. It is very diicult, expensive and someimes even dangerous to discover fossils and other historical evidence from the earth. Without fossils we would have a very vague understanding of evoluion if at all. To decipher history we must ind the fossils, put them in order and determine when they were formed. In order for a fossil to be formed the remains of the organism must ind its way to the botom of a body of water, become covered in sediment (so the body does not decay or get scatered) That"s why most fossils are of marine organisms. Once buried in sediments, the hard parts of the body are iniltrated/ replaced with dissolved minerals. What remains is a cast of the organism compressed into rock by building layers of sediment. Since the sot parts are not preserved, it makes it diicult to know very much of organisms back then.
