90 University of Kansas Geological Survey. 
these rocks, they were correlated with the Permian the upper forma- 
tion of which is called the Double Mountain division of Professor 
Cummins and is given a thickness of 2075 feet. It is stated that in 
this formation occur limestones containing “many casts of fossils” 
and numerous gypsum beds, some of which are very thick.! Over- 
lying unconformably the Permian Red-Beds is another formation 
also belonging in what is popularly termed the Red-Beds, called the 
Dockum division by Professor Cummins, the thickness of which he 
gives as 125 feet in northwestern Texas.2 This formation has been 
positively correlated with the Triassic system by Professor Cope on 
account of the discovery of reptilian genera which occur in this 
system on the Atlantic border. Professor Cummins studied the 
Panhandle region of Texas from Mobeetie north to the Canadian 
valley and then followed it into Oklahoma to a point opposite the 
lower end of the Wichita range, and saw only the Double Mountain 
formation. His inference in reference to southwestern Kansas was 
that ‘‘The older beds of the Permian may have been exposed farther 
northward in Kansas, but I am of the opinion that southwestern 
Kansas has only the uppermost beds.’* Professor Hay had already 
stated that the Kansas formation was “continuous to Red river 
and appears to be stratigraphically connected with similar rocks 
beyond,’ though the writer is of the opinion that he had not fol- 
lowed the Red-Beds across Oklahoma to the Red river. Professor 
Hill has represented the Red-Beds or “Permo-Trias” as extending 
from northern Texas nearly across Oklahoma to Kansas.° Their 
age, it was stated, ‘‘certainly ranges from Permian at their base, as 
shown by the investigations of Cope, Ball and White in Wichita 
county of Texas, to Triassic, as shown by Newberry and Marcou, in 
Texas and New Mexico, and probably Jurassic—continuing to the 
base of the Comanche series, as seen in the Cheyenne sandstones of 
Kansas.’ However after studying the Red-Beds of the Medicine 
1 Ibid., Second Annual Report, p. 402. 
2 See ibid., pp. 361, 424. 
3 Ibid., Fourth Annual Report, 1898, p. 11. 
4 Ibid., Second Annual Report, p. 421. 
5 Robt. Hay, Bulletin U. S. Geological Survey, 1890, No. 57, p. 25. Washington. 
6 Final Geological Report of Artesian and Underflow Investigation, Pt. III, 1892, 
Map showing ‘Geographic Features of the Texan Region’’ (Ex. Doc. 41 Pt. 3, 52d 
Congress, 1st ses.) See, also, map in American Journal of Science, 3d series, vol. 
XLII, 1891, p. 112. 
7 Ibid., p. 180. 
