54 THE PERMO-CARBONIFEROUS RED BEDS OF 



tresses, cones and minarets, pinnacles and peaks, shoulders and ridges, domes, 

 towers, chimneys, gullies, ravines, and all sorts of fantastic shapes have been carved 

 by erosion from the blood-red shales along the slope of the bluffs. 



"The face of the bluffs is frequently covered with fragments of gypsum, either 

 in the form of plates of transparent selenite or in the form of concretionary masses. 

 The selenite is usually found in seams running diagonally through the clay, and the 

 crystals weather out and reflect the sun from thousands of points, making the slopes 

 appear to be covered with glass, whence the name. Glass Mountains. 



"The thickness of the Enid formation is unknown, but it is probably not less 

 than 1,200 feet, and may reach 1,500 feet. The well at Fort Reno was started at 

 about the same level as the top of this formation and reached a depth of 1,370 feet, 

 the drill stopping in red clay. It is possible, however, that this well passed through 

 the Permian rocks into beds of Pennsylvanian age beneath. At Spencer, 12 miles 

 east of Oklahoma City, a well passed out of the Red Beds at a depth of 1,550 feet. 

 The greater part of this thickness, however, was in Pennsylvanian rocks. 



"Woodward Formation. — ^Above the Blaine are approximately 300 feet of rocks, 

 consisting chiefly of shales, sandstones, and dolomites, and distinguished from the 

 formations above and below by the prominence of dolomites and the absence of 

 gypsum. The formation includes all the rocks between the two conspicuous gypsum 

 horizons, the Blaine and the Greer, and in general it may be divided into three 

 members — the Dog Creek, the Whitehorse, and the Day Creek — which were all 

 recognized and named by Professor Cragin from localities in Kansas, except that 

 his term Red Bluff was preoccupied, and for it the name Whitehorse has been sub- 

 stituted. For the formation as a whole, from the top of the Shimer gypsum to the 

 base of the Chaney gypsum, the name Woodward is proposed, from the county in 

 Oklahoma, where the strata are well represented. 



"Dog Creek Shales Member. — The Dog Creek member is composed mainly of 

 clays, containing occasional thin ledges of magnesian limestone, which in places 

 grade into a fair quality of dolomite. 



' ' The ledges, however, are usually thin and rarely sufficiently conspicuous to be 

 worthy of more than a passing notice. Professor Cragin's original description of 

 this member is as follows : 



"The Dog Creek * * * consists of some 30 feet, or locally of a less or greater thickness, 

 of dull red argillaceous shales, with laminae in the basal part and one or two ledges of 

 unevenly lithified dolomite in the upper. The color of these shales resembles that which 

 prevails in most of the divisions below rather than of the terranes above Dog Creek." 



' ' In his second paper he modifies his description in this way : 



"In central Oklahoma it is a great dolomite formation, laminated dolomite occupying a 

 considerable part of the thickness." 



"In his second paper he suggests that the name Dog Creek be changed to Stony 

 Hills. The writer agrees that the name Dog Creek is, perhaps, not the best that 

 could be used, but in view of the fact that the dolomites which make up the Stony 

 Hills in eastern Blaine County belong to the Blaine formation, and do not belong 

 to the Dog Creek, there seems to be no good reason for using the name Stony Hills 

 to designate this member. 



' ' Studies made during the last 3 years have demonstrated that in many parts 

 of Oklahoma the thickness of the Dog Creek is much greater than that given by 

 Professor Cragin. Near Quinlan, in eastern Woodward County, the aneroid read- 

 ings indicate 225 feet as the thickness of these beds, measured from the top of the 

 underlying gypsums of the Blaine formation to the sandstones of the next higher 



