664 CENTRAL MINERAL REGION OF TEXAS. 



float, although this last is very abundantly made up of fragments of the older 

 rocks. 



Secondly. The Cretaceous beds along the borders, even including the fos- 

 siliferous limestones, in large degree, are chiefly shore line deposits composed 

 of material of local origin. 



Thirdly. The dip of the Cretaceous strata is not uniform in amount or 

 direction, the contacts with other terranes are very irregular, and there is no 

 relation of continuity between certain widely separated exposures. In other 

 words, if the restoration of the strata be attempted upon the theory of con- 

 tinuity, impossible conditions of folding and twisting must be conceived in 

 order to explain the present relations. 



Fourthly. There are numerous and important faults crossing the Creta- 

 ceousless area, which faults have had such effects upon the lower rocks as must 

 have certainly preserved some remnants of any capping terrane, and yet over 

 all the area there is nothing later than Carboniferous, and very little indeed of 

 that. 



Fifthly. The pre-Cretaceous faults raised portions of strata of very much 

 earlier date to positions elevated enough to leave them after ages of denuda- 

 tion as hi^h as the summit, or higher, of the Cretaceous strata afterward de- 

 posited about them. 



Sixthly. The inferior contacts of the Cretaceous are various, showing that 

 much erosion had occurred prior to their deposition. Moreover, the amount 

 of denudation in the region is vastly greater and its time equivalent far more 

 lengthy than could possibly be required for the removal of Cretaceous only, 

 and this erosion is far in excess of what has taken place in the Cretaceous 

 area. 



Seventhly. Old stream-courses are numerous, and the dominance of the 

 older stratigraphy in the drainage is the most prominent feature of the dis- 

 trict, in striking contrast to that of Cretaceous areas, even when denuded, 

 as in parts of the Pedernales Valley. 



Eighthly. In numerous places outside of the area referred to here the 

 Quaternary deposits are largely made up of Cretaceous debris, and in all those 

 sections where erosion has exposed the lower rocks, buttes, hills, and patches 

 of Cretaceous attest the former presence of that terrane across the denuded 

 tract. (Compare First.) 



