Markes E. Johnson
Contributor
Professor of Geology, Williams College, Williamstown, Massachusetts.
Primary Contributions (2)
Cambrian Period, earliest time division of the Paleozoic Era, extending from 538.8 million to about 485.9 million years ago. The Cambrian Period is divided into four stratigraphic series: the Terreneuvian Series (538.8 million to 521 million years ago), Series 2 (521 million to 506.5 million years…
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