726 TRANS-PECOS TEXAS. 



6. Quartzitic sandstone 10 feet. 



1. Limestone 30 feet. 



8. Brown quartzitic sandstone 12 feet. 



9. Thickly-bedded limestone, with oyster shell fragments and Exogyra texana 



at the base .• 28 feet. 



10. Brown sandstone '. 10 feet. 



11. Massive foraminiferal limestone, with Caprotina and Monopleura 28 feet. 



1 2. Band of large flat oyster shell 2 feet. 



13. Massive foraminiferal limestone 10 feet. 



14. Brown sandstone 9 feet. 



15. Calcareous sandstone, with much worn oyster shell fragments 2 feet. 



16. Brown sandstone 8 to 10 feet. 



It. Limestone, with fragments of large oysters, siliceous at lower edge 10 feet. 



18. Flaggy quartzitic sandstone 10 feet. 



19. Limestone, with oyster fragments and Area in finely comminuted shell 



breccia. Exogyra texana fossils ' 10 feet. 



20. Calcareous sandstone 15 feet. 



21. Caprotina limestone, with Area, Ostrea, and shell fragments 15 feet. 



22. Shell brecciate siliceous limestone 40 feet. 



23. Brown, yellow, and splotched thinly-bedded conglomeratic limestone ... 65 feet. 



24. Brown quartzitic sandstone 15 feet. 



25. Argillaceous (?) flaggy limestone, weathers in various colors from brown 



and yellow to red 50 feet. 



26. Pisolitic, arenaceous, limestone conglomerate 30 feet. 



27. Brown to yellow and red flaggy sandstone, same as 25 60 feet. 



28. Ferruginous quartzitic sandstone 20 feet. 



29. Arenaceous limestone 40 feet. 



Lower rocks are concealed by basin debris. 



The flaggy marble predominates in Yucca Mesa, giving a development of 

 nearly one hundred feet near the lower edge. It is a bright yellow to pur- 

 plish-blue rock, weathering in various shades of color from red to pale yel- 

 low, which is governed partly by the degree of metamorphism in different 

 places. 



No evidences of fossils were found in these flags. The character of much 

 of the quartzitic sandstone is similar to that of the basal sands. It is often 

 false laminated and gritty, evidencing very shallow water at the time of its 

 deposition. The coarse calcareous grit contains worn fragments of oyster 

 shells, and the siliceous limestone carries shell fragments, often in such great 

 abundance that it becomes a shell brecciate limestone. These also show cur- 

 rent action in their false lamination. 



Thirty feet below the Caprotina horizon a narrow horizon of Exogyra (sp. 

 ind.) occurs. The fossils were two to three inches long and resembled Exogyra 

 texana. Very near the lower edge of this bed, in Malone Mountain, there is 

 a band of gryphea m dark shaly limestone. 



The pisolitic limestone conglomerate is a marked feature of the Yucca bed. 



