190 HISTORICAL GEOLOGY 



period. Thus the climate of the Permian stands out in striking 

 contrast against the mild and uniform climate of the immediately 

 preceding period. The concentration of the extensive glacial ion 

 over low-latitude countries, instead of high-latitude regions, is at 

 present without adequate explanation. It must be confessed that 

 the perplexing problems of Permian climate are as yet far from 

 solved. 



Economic Products 



As already suggested, coal beds of considerable economic 

 importance occur in the Permian of the northern Appalachian 

 belt, France, Germany, Bohemia, Australia, Transvaal, and Brazil. 



Salt is obtained from the Permian strata of Kansas, Oklahoma, 

 and central Europe. 



Gypsum deposits, which are so widespread in rocks of Permian 

 age, are quarried in many states as Iowa, Kansas, Oklahoma, 

 Texas, New Mexico, South Dakota, and Colorado. There are also 

 important gypsum and potash deposits in Europe. 



Life of the Permian 



As compared with the preceding Paleozoic periods, the Permian 

 shows a decided decrease in numbers and diversity of organisms. 

 The known animal species of the period are to be reckoned by hun- 

 dreds only. The organisms of the Permian were in several ways 

 distinctly transitional in character between those of the Paleozoic 

 and Mesozoic eras. 



Plants. — All the principal groups of Cryptogams were repre- 

 sented much as in the Pennsylvanian, except that the Lycopods 

 were very greatly reduced. In fact the Lepidodendrons became 

 wholly extinct by the close of the period. The Equisetce and 

 Ferns continued to be prominent, the Tree-ferns particularly 

 becoming more common. 



From the standpoint of evolution, the most interesting changes 

 or advances occurred among the Gymnosperms. In addition to 

 the Cordaites, which continued from the Pennsjdvanian, Cycads 

 and Conifers are known for the first time, thus giving the flora a 

 decided Mesozoic aspect. 



Protozoans. — Foraminifers continued to be very abundant as 

 shown by their presence in marine limestones. Radiolarians were 

 present though they are not well known as fossils. 



