Vol. VIII] DUMBLE-GEOLOGY TAMPICO EMBAYMEXT AREA 133 



AGE OF THE CRETACEOUS 



The Tamasopa, San Juan, and Papagallos seemingly rep- 

 resent a long period of practically continuous sedimentation 

 as the Tamasopa grades upward into the San Juan and the 

 San Juan into the Papagallos, with no evidence whatever of 

 unconformability. 



While the exact contact between the Papagallos shales and 

 the Escondido beds was not seen, the relations of the two 

 formations in the valley of the Salado River east of the San 

 Juan Mountains warrant the statement that the Papagallos 

 underlies the Escondido, which is the uppermost stage of the 

 Cretaceous of Texas. 



According to Bose" the upper portion of the Meso-Creta- 

 ceous here represented by the Tamasopa is of Cenomanian 

 age and he correlates it on the basis of its paleontology with 

 the Lower Cross Timber or Woodbine sands of the Texas 

 region The few fossils found in the San Juan prove it to 

 be the equivalent of the Austin or Taylor and the Papagallos 

 underlies the Escondido. It would, therefore, seem fairly 

 well determined that the Tamasopa, San Juan, and Papa- 

 gallos are the time equivalents of the Upper Cretaceous of 

 the Texas section from the Woodbine to the Taylor, inclu- 

 sive and that so far no uppermost Cretaceous corresponding 

 to the Escondido or Webberville has been observed south of 

 the Tamaulipas barrier. 



Tertiary 



EOCENE 



The Eocene deposits of the Tampico Embayment area are 

 quite different from those of the region north of the Tamauli- 

 pas range. In the latter the beds are very fossiliferous and 

 both lithologically and faunally are identical with the various 

 subdivisions of the Lower and Middle Eocene which have 

 been recognized in Texas. 



While the Chicontepec beds somewhat resemble the beds 

 of the Lower Eocene of Texas lithologically, no fossils have 

 yet been found corresponding to those of the Midway, Wilcox, 

 o r Lower Claiborne. The principal forms occurring in them 



« Neue Beitrage zur Kentniss der Mex„ Kreide. 



