248 



E. C. CASE 



shows the easternmost appearance of beds which can be referred 

 to the Triassic. The reference is without paleontological evi- 

 dence, but there is certainly a bed of disturbed sandstone and 

 sands which fill a gap between the Permian and the Cretaceous. 

 West of Double Mountain the comparatively level surface is con- 

 tinued to the breaks of Blanco Canyon west of Spur in Dickens 

 County. Just east of the point where the road from Spur to 

 Crosbyton crosses the Blanco Canyon there is a small tributary 



Fig. I. — Contact between the Dockum (Triassic) and the Double Mountain 

 (Permian) beds near Blanco Canyon. The tilted layer just opposite the figure on 

 the left marks the line of contact. 



of the canyon; the road crosses this tributary on a layer of hard, 



bluish-green sandstone which is apparently near the dividing line 



between the Triassic and the Permian (see Fig. i); above it are 



the sands and clays of the Dockum, as attested by the plant and 



vertebrate remains, and below it is a break indicated by a stratum 



of tilted sandstone which in turn lies upon sandstones and clays 



of the Double Mountain. 



A general section of the Triassic at this point is as follows: 



Fine cross-bedded conglomerate, variable in thickness 5-20 feet 



Red clay shading into yellow above 40-60 



White, red, and maroon clay 20-40 



Light-brown clay shading into a white clay with gypsum, plant 



remains, Unio and Triassic vertebrates 10-30 



Bluish-green sandstone 3-4 



Cross-bedded and tilted sandstone and red clay of the Double 



Mountain formation 10+ 



