Il8 FROM FISH TO PHILOSOPHER 



At the beginning of the Permian an inland sea, invad- 

 ing from the south, had occupied the Great Plains from 

 Colorado to Ohio; then in the course of continental ele- 

 vation this sea was drained to leave in Kansas and Okla- 

 homa a dead sea which deposited deep beds of salt, and 

 these in turn were overlaid with hundreds of feet of red 

 mud, and finally with desert sands. Erosion leveled the 

 older Colorado Mountains, depositing fourteen thousand 

 feet of rich fossilized strata over the areas of Texas and 

 New Mexico (now exposed in the Guadalupe Moun- 

 tains); while as Utah, Nevada, Idaho, and Oregon were 

 pushed from sea level into high relief, volcanic activity 

 broke out in western North America for the first time in 

 the Paleozoic era, penetrating granitic faults from central 

 Mexico to northern California. This period saw the ele- 

 vation of the Ural Mountains in Eurasia and other 

 chains across southern England, Germany, and northern 

 France, while much of the rest of Europe was covered 

 for a long period by a great dead sea along the edges of 

 which were sandy deserts. 



In many areas of the world the Permian presents a 

 picture of marked continental elevation bringing in its 

 wake the inevitable climatic change. Between the early 

 Pennsylvanian and the opening of the Permian the mean 

 temperature in Europe and North America is estimated 

 to have dropped from 53° to 32° F. The withdrawal of 

 the great seas, which had covered so large a fraction of 

 the Pennsylvanian continents, removed the thermal in- 

 fluence of equatorial currents and the stabihzing effects 

 of large bodies of water, while the new mountain ranges 

 interfered with the winds and increased precipitation on 

 the windward side, decreasing it on the lee, so that des- 

 erts became more widespread than at any time up to 

 the present. The southern ice cap crept north to the 

 Tropic of Capricorn and glaciers spread at altitudes in 

 South Africa, Australia, Argentina, southeastern Brazil, 

 and India— there is even evidence of there having been a 

 small glacier near Boston. The Permian ice-age was, 



