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for rocks containing a cementing material to solidify than in the comparatively 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 translucent quartzite by the solidifying action of waters containing silicic acid. At Quarry, in the northern part of Washington 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 the 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 Shreveport, 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