146 SOUTHERN BORDER OF CENTRAL COAL FIELD. 



strata had been tilted to the northwest before the Cretaceous period; and as 

 the Cretaceous is found on or in contact with every stratum of the Carbon- 

 iferous and Permian, from the highest to the lowest, there is little doubt 

 that the Cretaceous strata at one time extended continuously from the foot of 

 the Staked Plains to the Cretaceous beds on the east, and that the present 

 exposure of the underlying Paleozoic group is due to their subsequent erosion. 



The Cretaceous formation in this part of the State belongs entirely to the 

 Lower or Comanche series. The beds have a thickness of about 200 feet 

 wherever seen, except on the upper South Concho River, where the thick- 

 ness increases to about 400 feet. 



A section made at Santa Anna Mountain will give a general idea of the 

 Cretaceous formation as observed in this part of the State. 



No. Strata. Feet. In. 



1. Compact limestone 8 



2. Limestone with fossils, silicified 2 



3. Limestone, compact 4 



4. Limestone, soft 66 



5. Shell concretion 6 



6. Sandy clay, white , 20 



1. Reddish clay 2 



8. Pack sand 50 



9. White loose sand 20 



10. Red clay 2 



11. Sandstone. 13 



12. Reddish clay, with bands of white sand 20 



205 6 



The following section was made at Cow Gap, a pass in the Brady Moun- 

 tains, in McCulloch County: 



No. Strata. Feet. 



1. Limestone, hard 20 



2. Limestone. . . 80 



3. Rotten limestone, with beds of sandy clay 100 



4. Pack sand 10 



210 



No. 1 in the above section had the same fossils as No. 2 in the section 

 made at Santa Anna Mountain. 



The principal fossils found and identified in this formation were Gryphcea 

 pitcheri and Exogyra texana. These Cretaceous strata rest directly and un- 

 conformably upon the clays and sandstones of the Carboniferous. 



