186 PERMIAN OF TEXAS AND ITS OVERLYING BEDS. 



occur, or in the massive gypsum deposits of the upper beds, do we find any 

 bluffs of considerable height. 



This formation was first reported as Permian, in 1852, by Professor Jules 

 Marcou, who was at that time geologist with the Pacific Railroad Survey, 

 from Fort Smith to the Pacific Coast. 



In 1868, Dr. Wm. De Ryee, in a report made for the Texas Copper Mining 

 and Manufacturing Company, and published by them, reported the red beds 

 of Archer County as Permian. Prof. Jacob Boll, formerly of Dallas, Texas, 

 in an article entitled " Geological Examinations in Texas," published in the 

 American Naturalist (Vol. XIV, pp. 684, 686, September, 1880), called these 

 red beds Permian. Since that time Prof. E. D. Cope, of Philadelphia, Pa., 

 has described, in the American Naturalist and elsewhere, many vertebrate 

 fossils coming from these beds as Permian species. Dr. G. C. Broadhead 

 also refers some of the beds at Colorado City to this series. Dr. C. A. White, 

 of the United States Geological Survey, published in the American Natural- 

 ist (Vol. XXI LI, pp. 109-128, February, 1889), an article describing the in- 

 vertebrate fossils of the Permian that had been collected by myself while 

 collecting vertebrate fossils for Prof. E. D. Cope, and also those collected by 

 him from localities which I pointed out during a five days trip in that field. 

 This, except a few smaller notices, is all that has been written on this subject. 



The estimated thickness of the strata of the Permian is about 2800 feet. 

 A detailed section has been made across the formation, but a general section 

 has not yet been made up so as to determine the exact thickness of the strata. 



The dip of the strata is about 40 feet per mile north 45 degrees west. At 

 one locality the dip was calculated by an actual instrumental measurement of 

 ten miles, and at another place of five miles, and at a great number of places 

 of smaller distances, so that the dip of the strata is well determined. It is 

 only at the western edge of the Double Mountain beds that there is any in- 

 crease in the dip, and in that locality the strata are so much distorted and 

 folded that it was difficult to get long lines of observation, so that the general 

 dip could be determined with anything like certainty. There were no faults 

 found nor any evidence of eruptive disturbances. 



For convenience the strata are here divided into three beds, whose correla- 

 tion with the Permian formation in other localities will not be attempted in 

 this report. 



Beginning with the lowest or eastern, we have: 



1. The Wichita Beds. 



2. The Clear Fork Beds. 



3. The Double Mountain Beds. 



These beds, from the nature of their constituents and of their formation, so 

 grade into one another that the exact line of demarkation is very obscure, 



