THE PERMIAN PERIOD 665 



conglomerate. From the stunted aspect of the fossils, and from 

 the association of the dolomite with gypsum, salt, etc., it has been 

 thought that the limestone and dolomite may be largely chemical 

 preciptates. Some parts of the Permian are, however, of marine 

 origin. 



The Upper Permian of central and western Europe contains the 

 thickest salt-beds known in any part of the earth. Near Berlin, 

 one of these salt-beds has been penetrated about 4,000 feet, and its 

 bottom has not been reached. In addition to common salt, salts 

 of potash and magnesium were locally (Strassfurt) deposited in 

 such quantity as to be commercially valuable. The world's supply 

 of potassium salts, with the exception of saltpetre, comes from 

 these beds. Like rock salt, these salts probably represent precipi- 

 tates from waters of enclosed basins under special conditions. 



The Permian Phase 



The typical Permian phase of the system underlies the larger 

 part of Russia (in Europe), and appears at the surface over a large 

 area in the southeastern part of that country. It is generally con- 

 formable on the underlying Carboniferous, and is partly marine 

 and partly non-marine. It contains salt, gypsum, etc., and also, 

 in some horizons, marine fossils. 



In southern Europe the Permian is of "aarine origin, for the 

 most part, and is generally conformable on the Carboniferous. 



Summary. Great areas in both Europe and North America 

 seem to have maintained a halting attitude near the critical level 

 during much of the period, while in both continents there were 

 considerable areas of dry land. In both continents there are beds 

 which accumulated in fresh water, in salt lakes or inland seas, and 

 on the floor of the epi continental seas. But the differences between 

 the continents are not less instructive than the likenesses. In 

 Europe the Permian period was distinguished by great igneous 

 activity, while in America activity of this sort is unknown. The 

 Permian of Europe seems to be more closely allied, stratigraphically, 

 with the Trias than with the Carboniferous, and while the same is 

 perhaps true of the western part of North America, the opposite 

 is true for the eastern part. 



