1894.] NATURAL SCIENCES OF PHILADELPHIA. 63 



OBSERVATIONS ON THE GEOLOGY OF ADJACENT PARTS OF OKLA- 

 HOMA AND NORTH WEST TEXAS. 



BY E. D. COPE. 



Through the cooperation of certain members of the Academy I 

 was enal)led to make an expedition in the interest of vertebrate pale- 

 ontology during the summer of 1893. The gentlemen who contribu- 

 ted the means for this exploration were INIr. Charles Cramp, Gen. 

 Isaac J. Wistar, Dr. Samuel Dixon, JNIr. Thos. H. Savery and Mr. 

 William Sellers. I had the privilege of the society and assist- 

 ance of Prof. Amos P. Brown, in charge of the Department of Geology 

 and Mineralogy in the University of Pennsylvania. Theexpedition 

 left Bismark, Dakota, July 10th, and completed its labor at Galena 

 in southwestern Missouri on September 4th. 



The month of July and thirteen days of August were occupied in 

 explorations in the Standing Rock and Cheyenne River Sioux Re- 

 servations in North and South Dakota. Near Fort Yates, N. D., 

 we examined the hills which are directly to the north of the fort 

 and extend northward. We obtained from them several fossils which 

 indicate their marine origin, and that they belong to the Fox Hills 

 epoch of Meek and Hayden. Tliese include sharks' teeth of the genera 

 Galeocerdo and Otodiis, and a fragment of a probable Chimerid fish. 

 The bluffs of the eastern escarpment of the Laramie formation ex- 

 tend across the plain at a rlistnnce of twelve miles west of Fort Yates, 

 and these were explored without result, except the discovery of a 

 few fragments of Dinosaurian bones. 



We made an expedition to the Laramie liluffs which border 

 Hump Creek in the northern part of South Dakota. This stream 

 rises in North Dakota, and after a course of perhaps thirty miles it 

 flows into the Ree (or Grand) River. Its valley is bounded by bail 

 land bluffs, but in only one portion of these did we find vertebrate 

 fossils. I owe my knowledge of this locality, as well as that which 

 I had previously visited in 1S92, to Miss Mary Collins, who has 

 spent much of her life as a missionary among the Sioux, and who has 

 the confidence of these people in a marked degree. One of Miss 

 Collins' assistants, a Sioux named Maza (Iron), had observed the 

 fossils, and served as my guide during botii the expeditions which I 



