WICHITA AND ANCESTRAL ROCKIES SYSTEMS AND THE TEXAS FORELAND 



247 



WESTERN EPEIRIC SEA 



CRETACEOUS LAND 



GULF COASTAL PLAIN 



MIDLAND BASIN 



CONCHO ARCH 



OUACHITA SYSTEM 



PENN. 



o a s- 7 € 



WEST TEXAS BASIN 



CONCHO ARCH 



(Mid-Pennsylvonian) 



FORT WORTH BASIN 



Fig. 15.10. Evolution of central Texas as idealized 

 the Ouachita orogenic belt. 



Strawn basin. The faults in the Llano uplift have formed narrow grabens, 

 and the three most prominent horsts over which the later strata are 

 flexed are called, from west to east, the Richland Springs, San Saba, 

 and Lampasas "axes." The Richland Springs axis forms the southern part 

 of the present Rend arch. See map, Fig. 14.1. 



The time of deformation of the Ouachita orogenic belt is believed 

 to be post-Kickapoo. As cited in the treatment of the Ouachita Moun- 

 tains a major unconformity across the Atoka, McAlester, Hartshorne, and 



along an eastwest section from the Midland basin to 



Savanna beneath the Roggy shale in the west end of the Arkansas Valley 

 is believed to mark the time of main deformation in the Ouachitas. This 

 accords with Cheney and Goss's interpretation of the Pennsylvanian 

 around the north and east sides of the Llano uplift. 



West Texas-New Mexico Region 



During Permian time, the foreland area in front of the Marathons was 

 divided into a number of irregularly shaped provinces which received 



