RED BEDS BETWEEN WICHITA FALLS AND LAS VEGAS 



249 



The discovery of Triassic vertebrates in the white clay con- 

 firms Cummins' location of the Permian-Triassic line at this point. 

 Just below the bluish-green sandstone which is regarded as the base 

 of the Triassic there is a layer of steeply tilted sandstone which 

 marks a decided disturbance, perhaps of only local significance. 

 Beyond Blanco Canyon the Triassic continues to the base of the 

 Staked Plains and is covered by the Tertiary, the lowest portion of 



Fig. 2. — Contact between the Dockum (Triassic) and Double Mountain (Permian) 

 beds on Mott Creek. Above the head of the pick is a light-yellow cross-bedded 

 sandstone; below is a solid red clay. 



which is a gravel containing many water-worn shells of Gryphea 

 and Ostrea. The red is again seen in the Blanco Canyon. Where 

 the party descended into the canyon a few miles southeast of Mount 

 Blanco the white Tertiary is underlain by a pink or reddish deposit 

 of clay which is probably of Tertiary age and composed of reworked 

 Triassic material. Below this there is undisturbed red clay, prob- 

 ably of Triassic age, though no fossils were found in it. Beyond 

 Blanco Canyon, in the vicinity of Lyman in Motley County, the 



