76 A GEOLOGICAL SURVEY OF LANDa 



able seam, and this is the seam which is now worked by the mines 

 on both sides of the Kio Grande. The vein is exposed in the bluffs 

 of the Rio Grande north of Olmos creek, and also in the bed of 

 this creek north of the mines. 



This coal was carefully examined and measured at four points 

 in order to make out whether there was any successive change in 

 its nature, from which an inference might be made as to its nature 

 under the country lying to the east of Eagle Pass. The measure- 

 ments were made in Shaft number 4 in the Fuentes mine, Mexico, 

 in the Dolch mine and in two pits on survey 166 in block 17, and 

 are as below: 



1. 



A Section of the Coal in Shaft Number 4, Fdentes, Mexico. 



Thickness 

 in inches. 



9. Cap rook, shale and sandstone — . 



8. Bone coal 6 



7. Impure coal 6 



6. Good coal, containing occasional small lentils of bone coal 30 



5. Mixture of fireclay and bone coal 3 



4. Good coal 14 



3. Shaly fire clay ....30 



2. Coal 6 



1. Fireclay - 



2. 

 A Section of the Coal in the Dolch Mine, North of Eagle Pass. 



Thickness 

 in inches. 



8. Cap rock, dark shale — 



7. Coal of good quality 22 



6. Bone coal 5 



5. Fire clay \% 



4. Coal 24 



3. Fire clay 20 



2. Coal 6 



I. Fire clay — 



3. 



Section op the Eagle Pass Coal in a Pit on the East Bank of Olmos Creek 

 Near the West Line of Survey 1G6, Block 7. 



Thickness 

 in inches. 



II. Cap rock, gray sandy shale 



10. Bone coal 9 



9. Bony shale Tvith pockets of coal 12 



