BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 3, pp. 219-230 April 22, 1892 



NOTES ON THE GEOLOGY OF THE VALLEY OF THE MIDDLE 



RIO GRANDE. 



BY E. T. DUMBLE. 



(Presented before the Society December 31, 1892.) 



CONTENTS. 



Page. 



Introduction 219 



Topography 220 



Geologic Structure 220 



Lower Cretaceous 220 



Upper Cretaceous 221 



The Val Verde Flags 221 



The Pinto Limestone 222 



The Eagle Pass Division 224 



Upson Clays 224 



San Miguel Beds 224 



The Coal Series 225 



Escondido Beds 227 



The upper Cretaceous Section 229 



Reynosa Beds 229 



Correlation of Rio Grande and Colorado River Sections 230 



[introduction. 



Tin; following statements arc based partly on observations made dur- 

 ing a trip from Eagle Pass to Edinburg by row-boat in the months of 

 May and June, lss*.), and partly on work in the region between Del Rio 

 and Eagle Pass during- the summer of 1891.* 



A portion of the area having been described by Dr. R. A. V. Penrose, 

 Jr., in the first annual report of the Geological Survey of Texas, in the 

 present article I propose to confine myself to that pari of the river 

 between San Felipe creek, near Del Rio, and Webb bluff, three miles 

 below the southern Line of Maverick county. A Line joining the two 



* The greater portion of tl iction above Eagle Pas was made in company with Mr. J. Owen 



who rendered valuable assistance bj In accurate knowledge of the region on both ddesol the Ititi 

 1 (rande, 



XXIX Urn Geol. Soc. \m., \ 01 . 3, 1891. \-\'' 



