510 K. T. HILL — THE COMANCHE SERIES. 



The Paluxy Sands. — North of the Colorado-Brazos divide the alternating 

 beds of the Trinity division are succeeded by a terrane of fine, white pack- 

 sand, oxidizing red at the surface, about 100 feet in thickness, resembling 

 very much the Trinity sands and hitherto confused with them. They out- 

 crop along the eastern edge of the Brazos valley, in Parker and Hood, and 

 also in Erath, Comanche, Coryell and Bosque counties. South of the Colo- 

 rado-Brazos divide they disappear, the Comanche Peak beds resting directly 

 upon the Glen Rose beds. These beds are especially conspicuous southwest 

 of Granbury, forming the timbered upland of that region. 



The Paluxy sands, which are so called from the town and creek of that 

 name in Somerville county, can first be separated from the Trinity sands in 

 Wise county at a point between Decatur and Alvord. At Decatur the 

 beds are well developed. In general character they are somewhat similar 

 to the Trinity sands. There are differences, however: the Paluxy sands 

 have none of the fine pebbles which characterize the base of the Trinity ; 

 and the Paluxy beds are rather calcareous and argillaceous in places, while 

 those of the Trinity are more ferruginous. 



At Decatur the Paluxy sands contain some layers of honey-combed and 

 very argillaceous limestone. The gradation from the Paluxy to the over- 

 lying and underlying beds at Decatur is also rather gradual. At Comanche 

 peak the sands form the plain upon which the butte stands, making a belt 

 of forest region surrounding its base. Here the beds have a thickness of 

 about a hundred feet, and are of character similar to that at Decatur. West 

 and south of Comanche peak they occupy a considerable area, while they 

 extend many miles down the Brazos, finally disappearing at the Bluff" mills, 

 near Kimball, where they make the shoals over which the river runs. 

 Jonesborough, Coryell county, is situated directly on the outcrop of these 

 sands, and the Lanham road northward from the town crosses it several 

 times. A few miles north of Jonesborough the sands have a thickness of 

 only about fifteen feet, showing their decreasing thickness southward. The 

 transition from the sands to the underlying Glen Rose alternating beds is 

 rather sharp, but that of the overlyiug beds is a little more gradual, for 

 which reason these sands are placed in the Comanche division. 



The sand is stratified, and occasionally cross-bedded, and there are local 

 hardenings. The color varies from gray to yellowish, and the amount of 

 ferrugination which is here found is variable. The sand is also marked by 

 the growth of forest timber, largely post-oak, though smaller growths, such 

 as sumac, also occur. The sands probably extend for a considerable distance 

 down the Leon valley, although it is difficult to determine their exact 

 extent on account of confusion with the drift of the Leon river, composed 

 of this debris. The sands appear only in scattered spots further toward 

 the south. Thus, east of Burnet, on the Mahomet road, they appear as 



