RED BEDS BETWEEN WICHITA FALLS AND LAS VEGAS 245 



the north in Oklahoma;^ this shows that there was to the east an 

 open sea whose eastern Hmits cannot be determined as the deposits 

 have been removed by erosion. The Wichita is composed largely 

 of sandstones, sometimes heavily bedded, and red and blue clays 

 sometimes with irregular shaly sandstones and local conglomerates. 

 The Clear Fork to the west is characterized by layers of impure and 

 dolomitic limestone distributed through a considerable thickness of 

 irregular beds of sandstone, shale, and clay, mostly of a red color. 

 The outcrop of the hmestone is approximately along the hne be- 

 tween Baylor and Archer counties. This formation has less of the 

 blue clay and more of the red, with less heavily bedded sandstones, 

 than the Wichita, but aside from the limestone the beds are so 

 irregular in position and distribution that little can be said con- 

 cerning their arrangement and, unless the appearance of the lime- 

 stone be taken as a dividing line, no demarkation between the 

 beds can be described. Farther west the Clear Fork is overlain 

 by a series of dark-red and mottled clays with some blue and gray 

 layers all characterized by the more regular bedding, the darker 

 red of the clay (jn general), and the presence of large quantities of 

 gypsum in irregular seams, layers of satin spar, and thick beds of 

 massive and semicrystaUine character. Gordon found it difficult 

 to distinguish between the Clear Fork and these beds (the Double 

 Mountain of Cummins) and so mapped the two as undifferentiated 

 Clear Fork and Double Mountain.^ To the author it is as difficult 

 to distinguish between the Wichita and the Clear Fork as it is 

 between the latter and Double Mountain. In following or crossing 

 the line drawn between the two last by Cummins, approximately 

 through Haskell and Vernon, in Texas, a decided change is notice- 

 able in the sediments. This is not to be readily detected in any 

 limited distance or thickness. As far as Haskell the beds are 

 similar to those found east and north of Seymour, that is, they are 

 typical Clear Fork, with a thin but persistent layer of gray or 

 purple conglomerate composed of small pebbles with a considerable 

 amount of cement. This is the layer which I have previously 



' Cummins, loc. cit.; Gordon, loc. cit.; Adams, Am. Jour. Sci., XII; Bull. Am. 

 Geol. Soc, XIV. 

 ^ Loc. cit. 



