THE PERMIAN PERIOD 



391 



the ends. From Newfoundland to Alabama and even into 

 Oklahoma the rocks were thus crumpled. The rocks of the 

 old Appalachian land had been folded more than once before, 

 and so the Permian deformation added little to the com- 



Fio. 412. An ideal representation of the west coast of Appalachia, during 

 the Paleozoic era. The ancient rocks on the east are being eroded, and 

 the sediments laid down in the sea gradually become finer westward. 

 (Modified after Willis.) 



plexity of their structure. The Paleozoic rocks in the great 

 trough, however, were now folded for the first time (Figs. 

 412 and 413). In Pennsylvania, the strata were bent into a 

 series of open anticlines and synclines (Fig. 46). Farther 



FIG. 413. The same, after folding of the Paleozoic sediments. The 

 unshaded portion shows the folds restored as they might have been if 

 they had not been affected by erosion. (Modified after Willis.) 



south, where deformation was greater, the folds were com- 

 pressed and overturned westward (Fig. 47). Here and there 

 the stiff limestone and quartzite formations were broken 

 and thrust over the adjacent rocks (Fig. 414). At the same 



FIG. 414. Closely folded strata in the southern part of the Appalachian 

 mountains. (U.S. Geol. Sure.) 



time the soft shales were crumpled and crushed beneath the 

 stronger beds. So numerous are these overthrusts in some 

 districts that the original folds cannot now be reconstructed. 



