158 SOUTHERN BORDER OF CENTRAL COAL FIELD. 



head, and then again we would have to crawl upon our hands and knees. 

 There were lateral openings at different places, but we kept in the main 

 opening. Most of the way the bottom was dry, but here and there a pool of 

 water would be found standing in a basin of calcareous rock. Stalagmites 

 covered the floor and stalactites hung from the top. We came to a place 

 where there was a descent of the bottom of the cave for several feet, and 

 lowering our candles into the opening, found on account of the gas they 

 would not burn, so we retraced our way to the entrance. This cave is in the 

 massive limestone, three miles down the Colorado River, on the west side 

 from the Sulphur Spring, and just below the mouth of Falls Creek. 



Other caves have large quantities of guano in them, deposited by the bats. 

 Some of these deposits are twenty feet thick, and are of unknown extent. 

 These caves will in the near future no doubt be fully explored, and their 

 valuable beds of guano put upon the market. 



CONCLUSIONS. 



The sections made at the various localities mentioned, which can not all 

 be published at this time, warrant the following conclusions: 



1. The lowest Carboniferous beds (omitting the Burnet marble and litho- 

 graphic stone strata, which may prove older) consist of blue and black shales 

 and limestone, with a strongly marked and persistent band of thinly bedded 

 black limestone, containing a highly characteristic and distinctive fauna. 

 This seems to skirt the northern border of the Silurian, from Indian Bluff, 

 Lampasas County, to Brady Creek, McCulloch County, as a fringe, and has 

 no great width. 



2. This is overlaid by a series of sandstones and shales with little lime- 

 stone, containing coal measure fossils throughout. 



3. This in turn is overlaid by a series of limestones, clays, and sandstones, 

 with probably two seams of coal 24 to 28 inches in thickness. 



4. The coal measure strata are overlaid to the southwest by Permian sand- 

 stone, limestone, and shales. 



5. The conglomerate found in the coal fields of the more northern part of 

 the State appears here also, scattered over the surface in larger or smaller 

 pieces. 



ECONOMIC GEOLOGY. 



COAL. 



There are three seams of coal in the Carboniferous formation, as observed 

 in this part of the country; only two of these will in any probability be of 

 commercial value. One of them, the lowest, is found on the Scurlock survey, 



