154 PROCEEDINGS OF THE AMHERST MEETING 



Iii the course of examination of subsurface material done last summer in 

 the laboratory of the Bureau of Economic Geology of the University of Texas, 

 a new discovery of Cretaceous fossils occurring in the same manner in the 

 Permian was made by Dr. W. M. Winton. These samples were from the 

 Slayden No. 1 well, drilled by the Lewis-Jones Syndicate, in the northwestern 

 quarter of section 25, block 101, in Culberson County. It is located about 15 

 miles southwest of the Troxel well and a few miles northeast of the center of 

 Culberson County. In this boring the drill first passed through a little more 

 than 60 feet of Pleistocene material. At 80 feet the rock consisted of lime- 

 stone. Then for nearly 300 feet the bedrock consisted of dolomite, gypsum, 

 8iid some anhydrite, certainly Permian in age, down to 380 feet. From this 

 depth down to 500 feet below the surface the drill passed through beds con- 

 sisting of a mixture of clay, shale, seme gypsum, gravel, and sand. Below 

 this depth again the samples examined extended down to 733 feet, and these 

 consisted almost entirely of dolomitic limestone of the type of the Permian 

 rocks found in the region. The general section of the boring can be briefly 

 described as follows : 



General Section of the Material penetrated in Sayles No. 1, Culherson County 



Feet 



Surface soil, gravel and sand; evidently Pleistocene 0-70 



Limestone, dolomite, and gypsum, Permian 70-380 



Marl with anhydrite and gypsum 380-390 



Marly material, clay, shale, sand, and gravel. Much of the gravel con- 

 sisted of worn and angular fragments of dolomite, worn and angular 

 pebbles of flint and pieces of sandy limestone and sandstone of a 

 chalk-like rock; also pebbles of quartz and "Red Beds'' sandstone, 

 glauconite, and pyrite. In this material Dr. Winton identified frag- 

 ments of oyster shells, Grypham washitcensis (Nepionic), Area 

 washitcensis (in pyrite), cidarid spines, Nodosaria texana, Tcxtu- 



hiria glooulosa, Anomalina, Globigerina 390-500 



1 )olomitic limestone, Permian 500-733 



A closer examination of the material penetrated between the depths of 390 

 and 500 feet makes it evident that it is a deposit in a cavern. It consists 

 mainly of Cretaceous and Permian debris and is entirely unrelated to the 

 general section of the Permian. The writer takes it to be of Pleistocene age. 

 There seems to be a mixture of differnt kinds of Cretaceous material, repre- 

 senting mainly the Georgetown or its equivalents. It is, of course, possible 

 that a cavern deposit might have been made at the time of the advance of the 

 Comanchean sea. The general geological conditions suggest that several hun- 

 dred feet of the Permian have been eroded in late Tertiary or Pleistocene time, 

 and that the base of the Comanchean lay much higher up than the present 

 surface of the land. If such was the case, it would be difficult to explain the 

 transportation of material to such great depth below the advancing sea. It 

 also appears that the material represents more than one formation of the 

 Cretaceous. To the present writer it seems most likely that the. cavern now 

 filled had developed after the elevation of the Permian series to its present 

 height, which probably took place at the end of the Mesozoic age or biter, and 



