BUILDING STONES. 651 



The Beaver Division includes in its Bluff subdivision some thick strata 

 which will afford blocks of very large dimensions. They outcrop in the can- 

 yons of the Llano River in Mason County, and in tributary streams from the 

 north in this region, as in the lower portions of Little Bluff, Bluff, and Leon 

 creeks. Good exposures occur in Cold Creek Canyon, Llano County, north 

 of Smoothing Iron Mountain, below Baldwin's Ranch. Their tendency to 

 weather black is against them, but their durability is unquestioned. 



The Wyo Division contains little material of this class which can be em- 

 ployed for architectural uses. 



The Hoover Division, besides the Burnet marble already described, has 

 near its summit some choice crystalline granular and saccharoidal limestones 

 which will become serviceable eventually, but some care will be necessary in 

 selecting, on account of the undesirable effects of weathering. 



A few of the Hinton layers may be worthy of trial, especially those near 

 the base of the division. The Deep Creek Division has also promising mate- 

 rial in its basal members, but unless the spongy chert be utilized in special 

 situations for artistic effect, the higher portion of the San Saba series is not 

 liable to be much used in construction. 



DEVONIAN AND CARBONIFEROUS. 



The rocks which I have provisionally placed as Devonian, and those of the 

 Carboniferous System lying within my district, are not, in the main, such as 

 will attract much attention from architects and builders, although some of 

 the lighter hued limestones may be adapted for their use. The outcrops are 

 very limited, except at the northern border of the Central Mineral Region. 

 The Devonian is usually too dark for most purposes. A little jet black chert, 

 sometimes mistaken for coal, occurs in the Riley Mountains and elsewhere; 

 this might be worked up as an ornamental adjunct, perhaps. 



CRETACEOUS. 



The Cretaceous limestones along the border of the Central Mineral Region 

 are usually less attractive than some of those farther eastward, but some lay- 

 ers have been successfully used locally in buildings. My examination of this 

 material from an economic standpoint has been but cursory, however. 



D. SANDSTONES. 



The sandstones of the district are abundant, but they represent few geo- 

 logic horizons. Aside from very limited exposures of serviceable material in 

 the Carboniferous (chiefly near Hamilton Creek, Burnet County, with a small 

 patch at the great bend of the Pedernales, southeast of Cypress Mill, Blanco 



