96 GULF TERTIARY OF TEXAS. 



Cherokee, it is found in many places south of Alto, and thence on into An- 

 gelina, Nacogdoches, Rusk, and other counties. On the bluffs of the Brazos, 

 lignite is exposed in various places, from the northern part of Milam County- 

 down to the southern part of Burleson County. The largest bed seen here 

 is at what is known as " Calvert Bluff," in Robertson County, near the town 

 of Calvert. A section of this bed is given on page 26. It will be observed 

 that there are two separate beds, the upper one twelve feet thick, and the 

 lower one two feet, and separated by two feet of clay. The lignite is black, 

 friable, of a somewhat woody structure, and crumbles on exposure to air. 

 Both above and below this point on the Brazos are seen numerous beds va- 

 rying from one to five feet thick. On the Colorado River, many lignite beds 

 crop out in Bastrop and Fayette counties. Both above and below the town 

 of Bastrop they are very numerous, and form an almost universal accompa- 

 niment of the sandy and clayey bluffs, varying from one to five feet thick. 

 Along the river, in the western part of Fayette, they are seen near the mouth 

 of Barton Creek, and in the First and Second Chalk Bluffs. See page 52. 

 Some eight miles by river above La Grange is seen a bed ten feet thick. 



SAN TOMAS COAL MINE. 



This is the only place where fuel is mined on any considerable scale east of 

 a line drawn between Eagle Pass* and Dallas. A section of this is given on 

 page 43. The coal bed is two and a half feet thick, and separated in the 

 middle by a two inch seam of hard black clay.f The coal is jet black, 

 highly glossy, and has a conchoidal fracture. It is generally massive, though 

 sometimes it has the structure of bituminous coal. It is light and friable, 

 and has the appearance of being an altered lignite. 



This material has proved a very serviceable fuel, and is especially valuable 

 in a country like Southern Texas, where there is no other coal, and where 

 wood is very scarce. The enterprising manager and owner, Mr. C. B. 

 Wright, has built a railroad, the "Rio Grande and Pecos," from the mine to 



^Considerable coal is mined a few miles northwest of Eagle Pass. 



f As will be observed in the section, the coal is both underlaid and overlaid by clays contain- 

 ing thin seams of true woody lignite. The presence of these throws some light on the cause 

 of the metamorphism of the coal into its present shape. If it had been due to any disturb- 

 ance in the strata of the surrounding country or connected in any way with the existence 

 of the eruptive knobs to the west and northwest, we should expect to see all the beds met- 

 amorphosed, and not the central one only, as they are so close together that any such influ- 

 ence that would affect one must also affect the other. Therefore we are driven to the con- 

 clusion that the change of character of the material must have been due either to the pecu- 

 liar conditions surrounding its deposition, or else to the chemical action which has taken 

 place since that time. Probably both these causes have operated, the chemical cause pos- 

 sibly having been started by the physical one. 



