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Unformatted text preview: ~ 570 Ma Proterozoic _______________________________________________ ~ 2.5 Ga Archean _______________________________________________ ~ 3.8 ? Ga Pre-Archean _______________________________________________ 4.5 Ga Please Note: There is some disagreement as the placement of the Quaternary Tertiary boundary. Some propose to move it back to the first appearance of widespread glaciation, which occur at about 2.5 Ma...
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- Fall '09