6 CONTENTS. 
Descriptive geology — Continued. Page. 
Tertiary — Continued. 
Eocene — Continued . 
Reconnaissance from Carrizo Springs to San Lorenzo Creek 47 
Nueces River section 47 
Reconnaissance from Uvalde to Carrizo Springs and from Carrizo 
Springs to Santo Tomas 
Frio River section 
Conclusions regarding the Eocene 
Neocene and Pleistocene 
Neocene 
Pleistocene 
Economic geology 
Eagle Pass coal field 
Extent 
Mines 
Character of coal 
Eocene coal fields 
Extent of the Eocene coal fields, including the Santo Tomas field 
Mines 
Character of coal 
Conclusions regarding the Rio Grande Eocene coals 
Literature 
II. — San Carlos Coal Field. 
Introductory note 
Geographic position of localities studied 
Literature 
Topography and structure 
Sections studied and notes thereon 
Peak 6 miles west of south from Chispa 
Sections in the vicinity of San Carlos 
Vieja Mountains east of San Carlos 
Fossils from same 
Detailed section through coal seam 
Arroyo northeast of shaft of San Carlos Coal Company 
Fossils from same - 
Overturned fold north of shaft of San Carlos Coal Company 
Fossils from same 
Sands and clays 
San Carlos and arroyo above 
Gettysburg Peak 
Resume of San Carlos section 
Age of fossils below the coal 
Bracks Canyon 
Geographic distribution of quartz-pantellerite 
Correlation of the Chispa and San Carlos sections 
Time of the volcanic outbursts 
Dikes 
Strata below the San Carlos formation 
Extent of San Carlos and other Trans-Pecos Texas coal fields and condition of 
mining 
Character of San Carlos coal, including analyses 
Report on igneous rocks, by E. C. E. Lord 
