22 



THE PERMO-CARBONIFEROUS RED BEDS OF 



"The development of the sandstones is irregular. They frequently change in 

 thickness, and may run out in a few hundred feet. They can seldom be traced in 

 continuous outcrop for more than a mile or two." 

 Texture. 



"The sandstones are fine in texture, about 85 per cent of the weight of the 

 sand consisting of grains measuring from one-fourth to one-sixteenth of a millimeter 

 in diameter. Grains measuring more than one-fourth of a millimeter are scarce, 

 constituting only a small fraction of i per cent, in case any such grains are present 

 at all. Compared with other sands the Wichita sands are well sorted. They contain 

 very little material in which the grains measure less than one-sixteenth millimeter 

 in diameter. In this respect the Wichita sand is a true beach sand. To plainly 

 present these characteristics, a few mechanical analyses have been made, as shown 

 [below]. Analyses of the three Cisco sands are also introduced for comparison. 



" Table showing the mechanical composition of sandstones in the Wichita and the Cisco formations, in 

 percentages of weights of different grades of coarseness. 



A, South of Bellevue, Clay County. 



B, 5 miles east of Henrietta, Clay County. 



C, Near Bellevue, Clay County. 



D, Averages for Clay County. 



E, Finder's Butte, 3 miles WNW. of 



Holliday, Wichita County. 



F, 3 miles west of Burkburnett, Wichita County. 



G, Wichita Falls, Wichita County. 



H, Butte on Palo Pinto School lands, Wichita County. 

 I, Tenth Cavalry Creek, Wichita County. 

 J, Electra red sand, Wichita County. 

 K, Average for Wichita County. 



"The Wichita sands do not appear to be greatly worn, for even the coarser 

 grains are not well rounded. The surface of the sand grains very generally shows 

 the effect of etching, being roughened or very irregularly pitted. This etching has 

 no doubt been effected by the solvent action of percolating ground water, which at 

 times probably has contained a comparatively large amount of alkalies in solution. 

 Characteristic Bedding in Sandstones. 



"We have already noted that in their mechanical composition the Wichita 

 sandstones resemble beach sands, or near-shore sands, being well sorted. Physical 

 conditions of this kind are also indicated by other features of sedimentation. In 

 a few places the sandstone is a freestone, showing no preferential planes of cleavage 

 in any direction, and no bedding planes of any kind. But no strata of this kind 

 were noted exceeding 4 or 5 feet, nor did these appear to run far horizontally. It 

 suggests itself that such beds may once have been small wind drifts on the sandy 

 beaches, which happened to remain undestroyed, and to be buried under other 

 sands later brought by the coastal currents of the sea. Usually these sandstones 

 are distinctly stratified and are built in layers from a few inches to a foot or two 

 thick. Sometimes these layers show a fine horizontal lamination. There extend 

 smooth and straight division planes horizontally in the stone for many yards in 

 both dimensions of a horizontal plane. These divide the layers into thin laminge 

 from a sixteenth to a fourth of an inch thick. Even the thinnest of these laminae 

 seem to be traceable for many feet, and with favorable weathering slabs of such 

 rock may be split into plates not much thicker than a card-board, and as large as 



