50 The American Geologist. July, i899 
granite hills. The material composing this arkose has been 
subjected to so little movement that it has not lost its angular 
character. 
Section — Bluff North Fork of Red River, east side of 
Stittle's Moimtai?i. 
3. Yellow river-sand composing top of bluff (second bottom). . 4 feet. 
2. White arkose 4 feet. 
1. Vermilion clay and arkose 10 feet. 
River bottom of sand and clay down to level of water in 
river 10 le.t 
The flats intervening between the separate mountain peaks 
or the groups of mountains are underlain by deposits that are 
somewhat problematic. They have been denominated by 
Cummins the Fort Sill series.''^ Comstock was inclined to con- 
sider the formation Tertiary. lie does not give any reason for 
this opinion. The material composing this Fort Sill series re- 
sembles in its lithologic character the Permian itself, composed 
of reddish argillaceous material, and extends from northward 
of the mountains toward the southward facing escarpment al- 
ready mentioned. On the north side of Rainy Mountain creek. 
15 miles southwest of Mountain City, the following section was 
observed that seems to belong to the same class of beds as 
those lying between the mountains. ^ 
3. Red clay 5 feet. 
2. White clay, some sand 4 feet. 
1. Argillaceous limestone. 
This formation is still problematic and we probably shall 
not be able to ascertain its relations until the area has been the 
subject of detailed investigation. 
The following section of Permian is made east of Fort Sill 
going toward Duncan. Section begins with No. i, the lowest 
bed exposed. 
5. Red sandy clay 130 feet. 
4. Stifif blue clay, blotched with deep wine red 20 feet. 
3. Clays blue or yellow, sometimes blotched red on spurs in 
lower part of the bed, yellow in the upper 120 teet 
2. Shaly gray sandstone forming cap of hill on top of divide 40 feet. 
(dip variable northeastward or northward) This 
sandstone forms a compact yellow sandy soil. The 
'''First Ann. Rep. Geol. Surv. Texas, 1890, p. 322, Austin. 
