74 A GEOLOGICAL SURVEY OF LANDS 



The Coal Series. 



These are the deposits which immediately overlie the San 

 Miguel beds on lower Olmos creek and at Eagle Pass. The series 

 consists of claj's, shales and sandstones, with seams of coal and 

 fireclay. One of the coal seams is thick enough to be profitably 

 mined. 



A continuous section of the coal series was made from the ex- 

 posures in the country around Eagle Pass, and this measures 357 

 feet. This section is as below: 



Section of the Coal Series. 



Thickness 

 in feet. 



20. Sandstone, tough and calcareous above and softer and more 

 siliceous below. (A part of the basal sandstone of the over- 

 lying Escondido beds.) 15 



19. Shaly clay 40 



18. Clay with yellow or dark concretions of carbonate of lime 

 and of iron, measuring from a few inches to three feet in dia- 

 meter, and having internal fissures filled with dark calcite... 1 

 17. Clay, sandy belo^v and with a dark carbonaceous seam 



about 12 feet below top 32 



16. Tellow and gray clay 3 



15. Laminated soft sandstone 1% 



14. Coaly shale 1% 



13. Sandy fire clay 1% 



12. Impure coal y, 



11. Fireclay 2 



10. Coaly clay 1 



9. Laminated sandstone 3 



8. Dark gray clay 1 



7. Laminated soft sandstone 3 



6. Coaly clay 2 



5. Clay, dark above and sandy in lower part 33 



4. Sandstone, in places cross-bedded, with occasional seams of 

 conglomerate of small pebble.i, slightly micaceous along 

 some seams, in its upper part containing silicified trunks of 



trees 40 



3. Clay, with seams of sandstone and occasional seams of 



coal 160 



2. Coal 6 



1. Fireclay and sandstone 15 



Numbers 1, 2 and 3 are not exposed in a continuous section 

 but were penetrated in such a section by an exploration shaft not 



