Geol— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 6'J 



"Division C," and both may be compared to the Volga 

 stage and similar deposits. 



Among the authors whose opinions are of more than 

 ordinary weight upon this topic may be mentioned the name 

 of Emil Haug (1898, p. 226). While conceding the Neoco- 

 mian equivalency of the upper portion of the Knoxville 

 (evidently the Paskenta), he plainly states that the lower por- 

 tion of the "Knoxville beds" undoubtedly corresponds to 

 the upper Portlandian of the Mediterranean region, which 

 he correlates with the upper Volgian, the Tithonian and 

 the Purbeck beds, and to the same horizon he refers the 

 Jurassic portion of the series found at Catorce in the State 

 of San Luis Potosi, Mexico. This seems to be on the 

 whole the most satisfactory correlation of these beds yet 

 suggested. 



5. CORDILLERAN OSCILLATIONS. 



The subsidence recognized independently for the regions 

 of Texas and California was synchronous throughout the 

 Cordilleras. It culminated with the close of the Comanche- 

 Knoxville epoch, attaining, probably, as great a depression 

 in these regions during the Cretaceous period as has since 

 been reached. The sea extended over western Texas and 

 eastern Mexico nearly, if not quite, to meet the waters of 

 the Pacific, which covered western Mexico. 



Following this period of depression was an epeirogenic 

 uplift of the Cordilleran continent, which threw the 

 shore-lines seaward upon both of its borders and thus cor- 

 respondingly expanded the terrestrial areas, and excluded 

 accordingly from the territory thus added to the continental 

 margins the contemporaneous deposits of the Dakota and 

 the Horsetown groups. 



Following the upHft of the Cordilleras were the disturb- 

 ances that resulted in the contemporaneous overlaps of the 

 Chico and of the Colorado, and the continued subsidence 

 of the remon until marine communications were estabHshed 

 between the interior basin and the Pacific Ocean, which 

 enabled species to pass from one to the other unobstructed. 



