7J8 TRA1JTS-PEC0S TEXAS. 



The Fredericksburg division is considered to end with the Caprina bed. 

 This agrees with the division made in the Colorado section, and is especially 

 agreeable with the structure of the rocks in the upper Colorado basin south 

 of Abilene. 



By examining the Colorado section the great development of the Fred- 

 ericksburg division with its Caprotina and Monopleura horizons and its Co- 

 manche Peak chalk will be observed. Then by considering the rocks of the 

 upper Colorado basin at the point above cited, it will be seen that the great 

 body of the Fredericksburg is entirely missing, that the development of the 

 Comanche Peak chalk has dwindled down to a mere band, and that the Ex- 

 ogyra texana bed lies immediately below the ever present Caprina chalky 

 limestone. 



This is exactly the case in the El Paso beds, as may be clearly seen in the 

 Flat Mesa section. 



TEXANA BED. 



Across the basin, north of Flat Mesa and about eight miles north of Sierra 

 Blanca Junction, there is a southward facing scarp, which extends westward 

 to the Hueco Mountains and eastward nearly to the Diabolo Mountains. From 

 the crest of the scarp an almost level plain extends northward towards New 

 Mexico. 



The best development of the Texana bed is in the face of this scarp, under- 

 lying the Caprina and Caprotina limestones which form the cap rocks. 



Below is a section |f the rocks at this point: 



1. Caprotina limestone * 10 feet. 



2. Caprina limestone with flint 40 feet. 



3. Calcareous ferruginous sandstone, with numerous Exogyra texana 2 feet. 



4. Ferruginous flaggy sandstone 10 feet. 



5. Siliceous limestone 15 feet. 



6. Ferruginous calcareous sandstone 10 feet. 



7. Limestone, disappearing beneath basin debris, exposed 20 feet. 



CAPRINA LIMESTONE BED. 



The Caprina limestone reaches a thickness of some forty feet, and with it 

 are flints, but not in great abundance. The presence of flints was observed 

 only in the exposures along the scarp four miles north of Flat Mesa. Tney 

 occur here in a narrow band, are small, and thinly scattered in the limestone. 

 The limestone is blue, hard, compact, and massive, and the change is so com- 

 plete through the general metamorphism that the original lithologic features 

 can not be readily obtained; but its massiveness and the presence of flints point 

 to a comparatively deep sea origin. So far as observed in the State elsewhere 

 the life is found to be a deep sea form. 



