Vol. VIII] DUMBLE— GEOLOGY TAMPICO EMBAYMENT AREA \\<) 



He describes the lower members of his Cretaceous tinder the 

 names of Tamasopa and San Fehpe, corresponding closely to 

 the Tamasopa and San Juan of our classification. To the 

 Mendez he refers the entire series of blue shales succeeding the 

 San Felipe and extending eastward to and beyond Mendez. 

 He gives these a thickness of 3000 to 3500 feet. In his section, 

 which is reproduced by various authors, he shows the Mendez 

 shales involved in the folding of the other Cretaceous rocks be- 

 tween Valles and San Felipe and states that the San Felipe beds 

 grade upward into the Mendez and downward into the Tam- 

 asopa. 



The base of the Mendez of Jeffreys is the equivalent of our 

 Papagallos, but the top is probably Tertiary. 



To the Tertiary he refers the fossiliferous beds around Tan- 

 lajas on the extreme western border of the area, the beds 

 around Ozuluama, which he considers practically their time 

 equivalent, and the overlying Temapache series. 



In Science for June 7, 1912, Dumble reported the discovery 

 of Eocene fossils at Alazan, northwest of Tuxpam, and gave 

 further details of the occurrence of the San Fernando and Tux- 

 pam beds (Miocene?) in this region. 



Garfias, in his article on The Oil Regions of Northeastern 

 Mexico", reviews the descriptions of the various formations as 

 given by different geologists, adds his own observations of the 

 region, and gives in tabular form a tentative correlation which 

 embodies the facts brought out after Jeffreys's report by the 

 finding of Eocene fossils at Alazan. This shows the Mendez 

 shales as originally described, including shales of both Upper 

 Cretaceous and Eocene age. 



De Golyer^ uses the names Tamasopa, San Felipe and 

 Mendez for the formations found in the Furbero field, but re- 

 fers both his San Felipe and Mendez to the Eocene, because 

 of the fossils found at Alazan. He also claims an uncon- 

 formity between his San Felipe and the beds he considers Cre- 

 taceous. 



Huntley'* also uses the same names for the same formations, 

 but regards the entire Mendez of Jeffreys as Eocene. 



' Economic Geology, Vol. X, p. 195. 



» Trans. A. I. M. E., LII, pp. 266 et seq. 



• Trans. A. I. M. E., LII, pp. 275 et seq. 



