PERMIAN. 41 1 



In No. 5 of the above section the seams of the fibrous gypsum form a per- 

 fect network, traversing the bed of clay in every direction, ranging in thick- 

 ness from that of a knife blade to ten inches. 



The massive gypsum of No. 4 in the above section is composed of round 

 concretions an inch in diameter, and has the appearance of pudding stone. 

 The matrix is white and the concretions are of various colors. This form of 

 gypsum I have seen at several places along the foot of the Plains. 



section no. 27. 



Made on Big Eed Mud Creek west of the Colorado and Dockum road. 



1. Red clay 20 feet. 



2. Red sandstone 4 feet. 



3. Red shale with seams of fibrous gypsum traversing in every direction 20 feet. 



Total 44 feet. 



A hill near the mouth of Little Mud Creek is capped with Triassic con- 

 glomerate. Near Section No. 27 is another hill with pieces of conglomerate 

 on the top. From this point to Dockum, fifteen miles, the strata are made up 

 of Permian and Triassic. The Permian was much eroded in places before 

 the deposition of the Triassic. 



These sections give almost a complete succession of the strata from the 

 contact between the Albany division of the Coal Measures Series and the 

 Clear Fork division of the Permian to the overlying Triassic The sections 

 of the Wichita division are given in another place. 



DETERMINATION OP THE AG-E OF THE STRATA. 



That there has been difficulty in proving positively the existence of the 

 Permian in the United States, any one at all familiar with the geological his- 

 tory of the country knows very well. This has resulted very largely from 

 the fact of the scarcity of fossils in the beds thought to be Permian, and from 

 the further fact that those who have attempted to determine the question have 

 undertaken to do so by trying to find fossils in the American Permian simi- 

 lar to those found in the Permian in Europe, and because the fossils found in 

 the American beds were not identical with those of Europe, the age of the 

 strata has been in dispute. In reference to the occurrence of fossils in these 

 beds there has been but one expression, and that is that they were very rare. 

 The conditions- necessary for their preservation did not exist except at rare in- 

 tervals during the entire time of the deposition of the strata. That the life 

 of that period was abundant there is no doubt, for where the conditions were 

 favorable to their preservation they are very abundant. At one place in 

 Texas I found at least twenty species in an area of five square yards in a bed 

 eighteen inches thick. 



