Vol. VIII] DUMBLE— GEOLOGY TAMPICO EMBAYMENT AREA 155 



Garfias^^ has described the mushrooming of these pkigs in 

 sending out sills of basalt through the bedded limestones. 



De Golyer^^ expresses the opinion that the lava cap was 

 originally continuous over a very large part of the area, and 

 that the flow occurred after the deposition and folding of the 

 entire series of marine sediments. 



The largest single body now remaining in this area is prob- 

 ably tliat of the Otontopec Range or Mesa, but there are many 

 other detached mesas and hills which still show their lava 

 covering resting upon the yellow, sandy clays of the Oligocene. 



History 



The movement, which, during the later portion of the Austin 

 Chalk period, caused the formation of the Sabinas barrier in 

 northern Mexico, was probably the beginning or directly con- 

 nected with the one that began the deformation which has re- 

 sulted in the present conditions of our area. 



East of the Sabinas barrier the Taylor, with its coal beds 

 and the overlying Escondido, were laid down with little, if any, 

 interruption, and are followed by the basal Eocene without 

 any evidence of an erosion interval between. 



One hundred and sixty miles south, at Ramones, on the 

 Salinas River, where we found the contact of the Papagallos 

 (which represents the Taylor, in some part, at least), and the 

 same basal Eocene, we see that the Papagallos has been 

 strongly folded and eroded prior to the beginning of Eocene 

 deposition. Similar folding is evident in the San Felipe- Valles 

 region. 



The initial movement in this area was, therefore, immedi- 

 ately following the deposition of the Papagallos and the fact 

 that between the Panuco and Tuxpam rivers not only the entire 

 thickness of Papagallos, but, in places, that of the San Juan 

 was removed prior to the submergence which permitted the 

 beginning of the deposition of the Eocene, indicates that the 

 erosion was very active. Farther south it was even more 

 active as the Rudistes limestone also seems to have been carried 

 away. 



The Midway or basal fauna of the Gulf Coast Eocene is 

 found as far south as the Tamaulipas Range but has not been 



'' Journal of Geology. Vol. XX, No. 7, p. 666. 

 "Trans. A. I. M. E. LII, p. 275. 



