CHAPTER 11. 



SUBSTANCE OF THE SKETCH OF THE GEOLOGY OF THE LOWER EIO BKAVO 



DEL NORTE. 



[By Arthur Schott, Assistant Surveyor, U. S. B. C. , &c.] 



Sir: la compliance with your instruction, I have the honor to subnait to you the following 

 description of the geological features of the country adjoining the Rio Bravo del Norte, from the 

 mouth of the Rio Puerco (Pecos) to the Gulf of Mexico. 



For the whole extent of country thus designated, I shall use the geological term cretaceous 

 basin of the Rio Bravo, to correspond to the upper basin, which may be proj^erly characterized 

 as the carboniferous metanio^-pJdc limestone. 



^^^^^^^^.^^_^.^;^_^ 



'P^A^/~^ r /j'^y '^I^ -r:U' 





Bank^ of the Rio Bravo del Norte, a-3 miles above the mouth of the Rio San Pedro, (Texas.) 



Commencing at the point where the Pecos empties its muddy waters into the Rio Bravo, we 

 find for a distance of about 50 miles a high table-land, consisting of solid masses of hard, dark- 



