PERMIAN PERIOD. 369 



last of the Trilobites, and the passing climax of the Brachiopods 

 and Crinoids ; of Ganoids and Sharks, but no Teliosts or Osseous 

 Fishes, that make up the greater part of the modern tribes ; of 

 Amphibians and some inferior species of True Reptiles, but no 

 Birds or Mammals ; and therefore there was no music in the groves, 

 save, perhaps, that of insect life and the croaking Batrachian. 

 Thus far had the world progressed by the close of the Carboniferous 

 period. 



The special history of the Coal period of Europe and Britain 

 might be followed out, as has been done for North America. But 

 it would illustrate no new principles, and would be more appro- 

 priate in a general treatise than in a text-book. More facts are to 

 be ascertained, before the details of the history are as clearly de- 

 ciphered. 



3. PERMIAN PERIOD (15). 



The Permian period, the closing era of the Carboniferous age, 

 was a time of decline for Palaeozoic life, and of transition towards 

 a new phase in geological history. 



The term Permian was given to the rocks of the period by Mur- 

 chison : it alludes to the district of Perm, in Russia, which is cha- 

 racterized by this formation. 



No division of the Permian period in America into epochs has 

 been recognized. 



1. AMERICAN. 



I. Rocks : kinds and distribution. 



The Permian rocks are confined to the Interior Continental basin, 

 and occur in the portion of it west of the Mississippi, — especially 

 in Kansas, and some parts of the eastern slope of the Rocky Moun- 

 tains. They overlie conformably the Carboniferous ; and, as the 

 rocks make one continuous series, it is difficult to determine the 

 limit between the two formations. 



In Nebraska and Kansas, they outcrop along the western border of the Carboni- 

 ferous region, in a strip running from Nebraska City southward (or a little west- 

 of-south), and also in patches to the east of this range. On the map, p. 133, 

 the Pei-mian is distinguished by light dots on a dark ground. The beds occur 

 also about the Black Hills (near lat. 44° N. and long. 104° W.), on the eastern 

 slope of the Big Horn Mountains, and, according to Shumard, in the Guadalupe 

 Mountains in New Mexico. 



The rocks are limestones, sandstones, red, greenish, and gray 

 marls or shales, gypsum beds, and conglomerates, among which the 

 limestones in some regions predominate. 



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