CONTENTS. 
Page. 
Letter of transmittal 9 
Introduction 11 
I. — Eagle Pass and Eocene Coal Fields of the Middle Rio Grande Region. 
Definition of area 13 
General physical features 13 
Descriptive geology 15 
Cretaceous 15 
Rio Grande section 15 
Lower Cretaceous (Comanche series) 16 
Edwards limestone 16 
Fort Worth limestone 16 
Del Rio clays 17 
Buda limestone 18 
Upper Cretaceous 18 
Dakota division (absent) 18 
Eagle Ford formation 18 
Austin chalk 19 
Upson clays 20 
Eagle Pass formation 21 
San Miguel beds 21 
Coal series 22 
Escondido beds 26 
Resume" of characters and thickness of the Eagle Pass for- 
mation 28 
Reconnaissance from Cline, Uvalde County, to Eagle Pass 28 
Reconnaissance from Eagle Pass to Carrizo Springs 30 
Studies along Turkey Creek and the Nueces River, the Frio and Sabinal 
rivers, Brackett and Uvalde quadrangles (eastern Kinney County 
and Uvalde County) 31 
Anacacho formation 31 
Eagle Pass formation in Brackett and Uvalde quadrangles 33 
Variations in character of the formations in the different sections 34 
Anacacho formation and Upson clays 34 
Eagle Pass formation 35 
Relation of the Cretaceous to the Eocene 35 
Rio Grande section 35 
Between Eagle Pass and Carrizo Springs 35 
Along the Nueces River 36 
Along the Frio River 36 
Tertiary 37 
Eocene 37 
Rio Grande section 37 
Reconnaissance between Eagle Pass and Carrizo Springs and 
southwest of Carrizo Springs 4<> 
5 
