191-'.] STEVENSON— THE FORMATION OF COAL BEDS. 485 



Mountains could not have become red by exposure during deposition, 

 for the playa beds in Nevada and similar regions are creamy white, 

 thoug'h the summer temperature reaches iio° to 120° in the shade. 

 The red color was acquired during decomposition of the rock and 

 consequent incrustation of the grains. Richtofen has explained the 

 red of the Rothliegende by supposing that during the Carboniferous 

 there was deep decay of the rock and that this material became that 

 of the Rothliegende. Russell applies the same explanation to the 

 great red deposits of America, which he regards as formed of debris 

 from rocks long exposed to a warm moist atmosphere. 



Beede's*^*' studies are in place here. It had been ascertained 

 that the light-colored sediments of Lower Permian in Kansas become 

 red in Oklahoma and the same condition was observed in going north- 

 ward into that state from Texas ; in one instance a limestone was 

 traced into a sandstone. Beede, following the Kansas deposits into 

 Oklahoma, found that limestones became sandy in patches, which 

 increased until the limestone disappeared. Farther south the sand- 

 stone becomes deep red or brown with patches of white. The lime- 

 stone fauna reaches southward only a little way beyond the limit 

 of that rock. Shales become red much farther north than do the 

 sandstones and often have deeper color ; even the limestone, at times, 

 becomes reddened before disappearance. The sandstones vary much 

 in thickness at expense of the shales, but the thickening is irregular, 

 the rock is cross-bedded and often shows ripple marks. At their 

 southern limit, the shales and sandstones dovetail into Permian con- 

 glomerate on the Arbuckle and Wichita mountains, which is formed 

 largely of the limestone, at one time covering those mountains and 

 even now 8,000 to 10,000 feet thick on their flanks. These lime- 

 stones yield a residual red clay, while the disintegrating conglomerate 

 yields a red sandy clay resembling that of the red beds. It would 

 appear that the lower red beds of Oklahoma were derived from the 

 Arbuckle-Wichita land mass and that the coloring matter is due 

 chiefly to solution of limestones known to have been removed from 

 the area. Beede concludes that the deposits, which are void of fossils 



""J. W. Beede, "Origin of the Sediments and Coloring Matter of the 

 Red Beds of Oklahoma," Science, N. S.. ^'ol. XXXV., 1912, pp. 348-350. 



