AMERICAN GEOLOGY DECADE OF 1850-1859. 453 



To Blake, too, fell the study of the collections made by Pope's expe- 

 dition along the route near the thirty -second parallel. It was the 

 original intention of Pope that this work should be done b} 7 Marcou, 

 but owing to the decision of Davis, then Secretary of War, the collec- 

 tions were returned by Marcou, as already noted, "in a confused con- 

 dition and with many of the labels displaced" and given to Blake. 



Captain Pope's route extended from Preston on the Red River in a 

 southwesterly direction to the Pecos River, and thence nearly due 

 west to the vallej^ of the Rio Grande at El Paso and Dona Ana in New 

 Mexico, crossing the Organ, Huerco, and Guadalupe mountains. The 

 result of this expedition was to establish the Carboniferous character 

 of the limestone of the Organ Mountains, the prevailing granitic type 

 of the Huerco Range, and the presumable Carboniferous age of the 

 limestone and sandstone of the Guadalupes (see also Shumard's obser- 

 vations, p. 434). The underlying formations of the Llano Estaeado 

 were judged from the specimens to be probably Cretaceous and not 

 Jurassic, as mapped by Marcou. For the geology of the region 

 between Llano Estaeado and Preston, Blake drew largely on Shumard's 

 publications. 



The origin of the gypsum beds he regarded as due to the action on 

 the underlying limestone of percolating waters containing sulphuric 

 acid derived from the decomposition of pyrites. 



Thomas Antisell accompanied the party under command of Lieut. 



J. G. Parke, surveying the route in southern California to connect 



with the routes near the thirty-fifth and thirty-second parallels and 



also the route near the thirty-second parallel between 



Antis£u rk ° f the Rio Grande and Pinias Village, v which was explored 



by^ Parker in 1854-55. 



Antisell recognized the post-Miocene age of the final uplift of the 

 Coast Range and thought that the elevating force must have taken 

 place from two points, one in the north and one in the south, and that 

 the forces became gradually spent as the} T passed, one in a southerly 

 and the other in a northerly direction toward each other. He con- 

 ceived that this resulted in an uplifting of the consolidated crust of 

 the State at either end, while the center remained quiescent, causing 

 thereby a rupture of the superficial strata, or even a depression below 

 sea level near the middle, forming thus San Francisco Bay. 



Influenced to some extent by Eliecle Beaumont's theory of mountain 

 uplift and the relative age of mountain ranges, as indicated by their 

 parallelism, he, without committing himself in any way, called atten- 

 tion to the north and south trend of all the New Mexican ranges and 

 northwest and southeast trend of the Sierras, the Coast Range, and 

 the ranges of Nevada. 



No Paleozoic rocks were recognized in the southern part of the 

 State. The sandstone underlying the Carboniferous limestone of the 



