CLAY-. 89 



for rocks containing a cementing material to solidify than in the compara- 

 tively moist and mild climate to the north. 



2. There is a greater amount of carbonate of lime disseminated through 

 the sand beds of the Rio Grande than to the north. This acts as a cement, 

 and solidifies the mass. A rock of this kind is extensively worked near 

 Laredo, for building and paving purposes. It splits easily into slabs, is 

 highly calcareous, and often very hard. 



The sands of the Fayette Beds frequently are sufficiently hardened to be 

 used for building. Sometimes they have been converted to a massive trans- 

 lucent quartzite by the solidifying action of waters containing silicic acid. 

 At Quarry, in the northern pan of TVashington County, large quantities of 

 this rock are taken out and shipped to Galveston and Houston for building 

 foundations, jetties, etc. 



LIMESTONES. 



The limestones of the Tertiary region of East Texas are rare, but where 

 they do occur they often offer an excellent source of durable and strong 

 building stone. They are generally hard, highly siliceous, and of a gray 

 color. They are of limited extent, and probably occur as lenticular beds. 

 They are usually in association with salines, though not invariably so. There 

 are also found white limestones, like that at the Saline, in Anderson County. 

 but these are rare, and better adapted for iron smelting than for building 

 stones. As none of the gray limestone beds have as yet been seen by the 

 writer, they can not be treated in detail. Rocks of this kind from a- saline in 

 eastern Freestone County are used in some of the railroad culverts east of 

 Oakwoods. in Leon County. They are also found in trie Saline in northern 

 Smith County, and also in a similar locality in the southwestern corner of 

 the same county. The large nodules of limestone at Port Caddo, in Marion 

 County, are said to have been broken and used for paving streets in Shreve- 

 port. La. On the Rio Grande, at Roma, a Quaternary bed composed largely 

 of white limestone carrying a variable quantity of rounded river pebbles is 

 sometimes used for building purposes. In that dry climate it answers the 

 purpose excellently, though a moister atmosphere would doubtless rapidly 

 decompose it. 



Thus it will be seen that East Texas, though as a rule underlaid by soft 

 strata, contains also many localities of harder rock, and there is scarcely a 

 town in the country that can not get sufficient rock, at least for foundations, 

 and in many places for more extensive structures. 



CLAYS. 



Clays suitable for the manufacture of fire brick, earthenware, and even of fine 

 china, are found in East Texas. Two companies are now engaged in making 



