Research topic: Permian period

Permian period [from Perm, Russia], sixth and last period of the Paleozoic era (see Geologic Timescale , table) from 250 to 290 million years ago. Historical Geology of the Period The Lower Permian During the Permian period, changes in the earth's surface that had begun in the preceding Carboniferous period reached a climax. At the close of the Carboniferous, large areas of E North America were dry land. In the Lower Permian, sandy shales, sandstones, and thin limestones of the Dunkard formation (formerly called the Upper Barren measures) were deposited in the remaining... Read more