502 GEOLOGY OF NORTHWESTERN TEXAS. 



is a thick bed of shales with hard sandstone concretions covered with crys- 

 tals of selenite. This is evidently the same seam and bed of coal traced from 

 the mouth of Sandy Creek, Stephens County, to Flat Top Mountain in the 

 eastern edge of Young County. In the limestones and shales are a great 

 many Myalina subquadrata. 



To the eastward of this place the coal outcrops near the top of the hills in 

 several places. Two miles northeast of Carbondale and about one mile south 

 of the G-ilfoil shaft the coal outcrops in the banks of a branch, showing the 

 same shaly sandstone usually found above the seam of coal in this vicinity; 



TOPOGRAPHY AND DRAINAGE. 



The dip of the formation being to the northwest gives several lines of es- 

 carpment m the county running from northeast to southwest. These escarp- 

 ments are of various heights, according to the thickness of the soft material 

 underlying the several beds of harder material. In places these escarpments 

 have been cut across by the rivers and creeks, and the result has been isolated 

 hills of various sizes and shapes, some of them rising to the height of two 

 hundred to five hundred feet above the surrounding country. The highest 

 points in the county are the Belknap Mountains, situated east of Fort Bel- 

 knap on the Graham road. Flat Top Mountain is near the northeast corner 

 of the county, and being in the prairie can be seen for many miles from 

 every direction. The valleys and much of the uplands are level and are 

 well adapted to agricultural purposes. Some of these lands are remarkably 

 fertile. 



GEOLOGY. 



This county is situated entirely within the Coal Measures. Mr. Chas. A. 

 Ashburner reported that the Sub-Carboniferous formation was found in this 

 county, but after a very careful examination of the county I am sure that the 

 only formation found here is that of the Upper Coal Measures. Certainly 

 there is no Sub -Carboniferous. It may be that the northwestern part of the 

 county will be found to be Permian upon a more detailed examination than 

 I had time to make. 



The strata comprise sandstones, limestones, clay beds, and conglomerates, 

 in beds of various thickness. The conglomerates are composed of rounded 

 water- worn siliceous pebbles, and often pass into coarse grained sandstones. 

 The limestones have various colors and degrees of hardness. The clay beds 

 are often very thick and are red, blue, yellow, and variegated. 



