REPORT OF THE STATE GEOLOGIST. lxix 



from which they are principally derived, and are as varied in quality as 

 in kind. Many of these are very fertile and produce good crops. 



At the close of this period the southern shore line, which had prob- 

 ably been somewhere below the 31st parallel, was moved northward by 

 the elevation of the old sea bottom into a land area, and its surface 

 was in turn exposed to erosion, and the results of this denudation went 

 to form the deposits of the succeeding system, which we know as the 

 Permian. 



PERMIAN SYSTEM. 

 WICHITA BEDS. 



The Permian deposition is marked by three distinct periods. In 

 the first of these beds the shore line was probably not far south of the 

 present Brazos River channel in Throckmorton and Baylor counties, 

 for no deposits of the Wichita Beds are found south of that point. The 

 rocks are sands and clays with many concretions — siliceous, ferrugin- 

 ous, etc. In places copper ore is found in greater or less quantity, 

 principally as a pseudo-morph after wood; sometimes, however, as 

 nodules or segregations. And here are also found in the different 

 strata the remains of many vertebrates and plants. 



CLEAR FORK BEDS. 



Following the deposit of this division of the Permian, the sea grad- 

 ually encroached upon the land and drove the shore line southward 

 beyond the Colorado River in Concho County, and the Clear Fork lime- 

 stones and underlying and overlying clays and sandstones were laid down 

 therein. Some of these limestones are more or less argillaceous; all are 

 magnesian, and in some of the upper seams they carry small quantities 

 of galena scattered through the occasional bands of limestone. Toward 

 the upper portion these beds also contain some gypsum, and thus mark 

 the advancing conditions of the Double Mountain Beds. 



The clays and sands of these Clear Fork Beds are all more or less cal- 

 careous, and contain gypsum in small quantities, and the resulting soils 

 are therefore of great fertility. The life of this age, as shown by fossils, 

 was principally of shell fish and corals in the earlier portion, while in the 

 upper we find plants and vertebrate remains and the tracks of articulates. 



In these upper strata also we find other deposits of copper similar 

 to those of the Wichita Beds. In one locality, near California Creek, 

 we found the remains of a tree, a portion of which was cuprified while 

 the balance seemed to be silicified. 



