WICHITA AND ANCESTRAL ROCKIES SYSTEMS AND THE TEXAS FORELAND 



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Fig. 15.14. Idealized section after Lovering (1929) of the Colorado Range near the close of 

 Pierre time (Upper Cretaceous) and before deformation during the Laramide revolution. Kp, 

 Pierre sh.; Kn, Niobrara Is.; Kb, Benton sh.; Kd, Dakota Si.; Jm, Morrison fm.; Je, Entrada ss.; Js, 

 Sundance fm.; Cp, Belden sh.; Maroon fm. (Des Moines) and State Bridge siltstone (Permian); 



County, apparently continuously to northern Torrance County. Very 

 coarse conglomerates with cobbles of quartzite and other metamorphic 

 rocks are present in the Pennsylvanian rocks in the Sacramento Moun- 

 tains on the west side of the uplift. From these and other similar data, 

 Thompson concludes that the Pedernal Range was in existence from 

 early Pennsylvanian time until well after the beginning of Permian time. 



The Colorado Range probably extended southward into New Mexico 



through Colfax and Mora counties. Very thick sections of Pennsylvanian 



j rocks of Des Moines age or older crop out on the eastern edge of the 



| Sangre de Cristo Range from the region of Pecos River almost to the 



! Colorado border. These rocks include arkoses, arkosic conglomerates and 



I sandstones, and black shales. 



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1 Zuni Uplift 



In northwestern New Mexico and northeastern Arizona evidence of 



Pennsylvanian uplift is noted in the modern Zuni and Defiance ranges. 



With additional subsurface evidence from drilling the configuration of 



; the range appears to be like that illustrated in Fig. 6.7. Red sandstones 



and shales identified as the Permian Ajo formation rest on Precambrian 



Cml, Leadville Is. (Mississippian ?); DO, Devonian and Ordovician formations; Cs, Sawatch 

 quartzite; Cpf and Cpl, Fountain fm. and Lykins fm. (Pennsylvanian and Permian ? red arkosic 

 ss. and congl.); Cmm, Millsap fm. (Mississippian); Ofhm, Fremont Is. (Ordovician); Cq, Cambrian 

 quartzite. Vertical scale exaggerated and relative thicknesses of formations only approximate. 



crystalline rock in the Zuni Range, and the Permian Moenkopi formation 

 rests on the crystallines in the Defiance Range. The old uplift is desig- 

 nated both as the Zuni and Defiance, but Zuni seems to be preferred. 



Florida Uplift 



In the Florida Mountains of southwestern New Mexico, Permian lime- 

 stone rests on Ordovician limestone; and a short distance to the north 

 in the Cooks Range, the Permian rests on Mississippian limestone. The 

 absence of Pennsylvanian strata is due to a Pennsylvanian or post-Penn- 

 sylvanian disturbance, probably at the same time as those in the south 

 end of the Hueco Mountains and the Diablo Mountains near El Paso. 

 The direction in which the elevated land trends is believed to be south- 

 easterly. It will be called the Florida Range. 



Burial of the Ancestral Rockies 



During Triassic, Jurassic, and Cretaceous time the Ancestral Rockies 

 were gradually buried by accumulating sediments. Immediately around 

 them were their own waste products, but marine epeiric seas brought 

 carbonates and fine elastics from adjacent regions, and these sediments 



