Mean atmospheric O2
Geologic Time Scale
Late Cretaceous Earth
This is how the western hemisphere of the Earth may have appeared 90 million years ago during the Late Cretaceous period.
During this period continental drift, driven by the massive forces of plate tectonics, had broken the supercontinent of Pangea into Laurasia in the north and Gondwana in the south. With a climate much warmer than today's there were no frozen polar caps and the resulting high ocean levels submerged a third of today's landmasses under warm shallow seas creating numerous waterways and "island" continents.
In this image much of the incipient North American continent is divided by the Western Interior Seaway, the Isthmus of Panama is submerged by the Proto-Caribbean Sea, and the Pacific Ocean is making an incursion into South America.
Copyright © Walter B. Myers. All rights reserved.
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