430 THE PERMIAN PERIOD 



In Texas the Lower Permian ( Wichita beds) is. principally com- 

 posed of sandstones and clays, in which some marine and some 

 land fossils occur. The Middle Permian {Clear Fork beds) is 

 largely made up of limestones, and represents a transgression of 

 the sea westward, for these strata often rest directly upon the coal 

 measures, without the intervention of the Wichita. In the Upper 

 Permian {Double Mountain beds) we find evidences of a closed 

 basin, like that of Kansas and Oklahoma, in the numerous beds of 

 gypsum, and in the quantity of salt which impregnates the shales 

 and clays. Occasional incursions of the sea into this basin are 

 indicated by the interbedded bands of fossiliferous limestone. 

 Westward from Texas the inland Permian sea extended to the 

 Pacific land area, and in it were laid down the rocks of this age 

 found in southern Utah ; these are masses of sandy shales, with 

 much disseminated gypsum and very few fossils. In the Grand 

 Canon district the Permian beds are remarkable for their rich 

 colouring. The inland sea also extended northward around the 

 Colorado islands, and traces of its presence are found to the west 

 in the 650 feet of Permian sandstones and shales in the Wasatch 

 Mountains. Whether the Permian strata have all been swept away 

 from Utah west of the Wasatch and from Nevada, or whether they 

 were never deposited there, is a question that cannot yet be 

 answered. In all this great interior sea of the West there is evi- 

 dence that the deeper waters of Carboniferous times gradually 

 gave place to shallow-water conditions in the Permian. 



Foreign. — In Europe the Permian is developed in two entirely 

 distinct facies or aspects. In central and western Europe the dis- 

 turbances which closed the Carboniferous resulted, in many places, 

 in a marked unconformity between the Carboniferous and the 

 Permian, while in other regions there is a gradual transition from 

 one system to the other, as in North America. The result of 

 these oscillations was the formation of a great inland sea, extend- 

 ing from Ireland to central Germany, in which were laid down 

 thick masses of red sandstones, shales, and marls. Occasionally 

 the ocean broke into this closed basin, bringing a marine fauna 

 with it, but only for comparatively short times. The disturbances 



