CHAPTER XXII 

 THE PERMIAN PERIOD 



FORMATIONS AND PHYSICAL HISTORY 



At the close of the Pennsylvania!! period much of the central 

 and eastern parts of the United States became dry land, and the 

 sea-covered area in the west was greatly restricted. The area of 

 land was perhaps as large as at any time since the beginning of 

 the Paleozoic. The waters which still lay upon the continent were 

 partly in the form of lakes and inland seas, and partly connected 

 with the open ocean, but the areas which the sea overspread at the 

 beginning of the period were largely abandoned before its close. 

 These changes in geography reflected themselves both in the distri- 

 bution of the Permian formations and in their character. 



East of the Mississippi. Fresh-water sedimentation continued 

 much as before during the earlier part of the period in some parts 

 of the east (parts of Pennsylvania, West Virginia, Maryland. 

 and Ohio), and with the other formations there is some coal. 

 The Appalachian belt farther south seems not to have been the site 

 of deposition. In Nova Scotia, New Brunswick, and Prince Ed- 

 ward Island, non-marine Permian strata rest on Carboniferous beds 

 in such a way as to show that sedimentation was not seriously 

 interrupted, and the two systems are separated on the basis of 

 fossils, as in the eastern part of the United States. 



West of the Mississippi. The system is better developed west 

 of the Mississippi than east of it. It is best known in Texas, Kansas. 

 and Nebraska, where it is partly marine and partly non-marine. 



In Kansas and Nebraska the lower part of the Permian is ma- 

 rine, and though the connection has not been traced, the Permian 

 of these states is probably continued northwestward to \Y\ online 

 and South Dakota, for marine Permian beds in the Laramie Moun- 

 tains and the Black Hills have fossils very similar to tlms-- <>f Kan- 



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