410 DRAKE — THE GEOLOGY OF INDIAN TERRITORY. [Sept. 3, 



reported it a little over four feet thick. The coal is apparently of 

 uniform good quality. This bed is now being worked extensively 

 at Cherry Vale, about three or four miles northeast of Krebs, where 

 it averages about three feet four inches thick, is uniformly good 

 and dips about 12° N. From this mine the coal outcrop runs 

 but little farther west before it swings to the south and then turns 

 east some twenty miles, when it again swings to the south and 

 back west again, thus forming an S-shaped outcrop at this place. 

 The eastward loop of the S outlines a small synclinal basin called 

 by Dr. H. M. Chance the Grady basin. ^ Coal is extensively mined 

 in this basin at Hartshorne. The coal is composed of one four-foot 

 bed, which is worked, and other higher, thinner beds, not worked. 

 The synclinal fold, forming the basin, is a gentle one so that the 

 dip of the rocks on its sides are only 4° to 5°. Chance ^ says : "The 

 maximum depth of the Grady coal bed in this basin is about 600 

 feet ; but over three fourths of the basin the bed can be reached at 

 depths less than four hundred and fifty feet, and over one-half of 

 the basin the depth will probably not exceed three hundred feet. 

 The basin is about six miles long by three or four wide and con- 

 tains over 11,000 acres of the Grady bed. Throughout this area 

 the coal is not always of workable thickness ; but over a large por- 

 tion of it the bed will range from three and a half to five feet 

 thick, yielding an average of four feet of clear coal." 



This coal outcrop west of Hartshorne is so broken by faults 

 and tilted by very irregular folds that it is not easily located. 

 The three-foot bed of coal that outcrops in Brushy creek, about five 

 miles west of Hartshorne, appears to be the Grady bed. Here it 

 shows a fault of four or five feet and dips to the southwest 5° to 6°. 

 About two miles further west, that is, seven miles west of Hartshorne 

 and one-fourth of a mile northeast of the Brunton place, this coal 

 outcrops again and is three feet eight inches thick, but with two part- 

 ings of shaly coal in it. One three to four-inch parting is within 

 three inches of the base, and ten inches from the base of the bed 

 there is a shaly parting from one to two inches thick. 



McAlester Coal Bed. — The outcrop of the McAlester coal bed 

 is greater than that of the Grady bed, since it does not lie so 

 deep and does not require such excessive foldings to bring it up or 

 such profound erosion to reach it. The outcrop is shown on PL I 



1 Trans. Am. Inst. Min. Eng., Vol. xviii, p. 654. 

 ^ Ibid., p. 659. 



