IN THE UPPER niO GRANDE EMIIAYMENT IN TEXAS. 81 



6. To the upper claj^Irefer provisionally all of the Cretaceous 

 sediments which lie above the upper sandstones. In the south 

 half of survey 116 in block 6 these beds were made out to be as in 

 the following- section. 



Section or the Uppermost Cretaceous Beds in Survey 116, Block 6. 



Thickness 

 in feet. 

 5. Soft sandstone of fine texture, yellow, with some layers of 

 more calcareous material, containing Sphenodisciia and small 



bivalve shells, preserved mostly as casts 15 



4. Clay with cakes of fibrous barite 20 



3. Brecia of broken oyster shells with sandy material 2 



2. Clay with shells of Ostrea cortex .52 



1. The upper sandstone : 5 



On the south side of Peiia creek, four miles south of the hill 

 where the above section was noted, the sandy member (number 5) 

 has a considerably stronger development, and measures some 40 

 feet. Above it was a clay of at least the same thickness. This clay 

 is characterized by the presence of Ostrea, idriensis and by an as- 

 semblage of other bivalves and some tall-spired gasteropods. The 

 same clay, with the same fossils, was noted in the northeast quar- 

 ter of survey 153 in block 7 and also in the southwest quarter of 

 survey 121 in the same block. It is overlain at all three places by 

 sandstones belonging to the Tertiary age. 



THE PULLIAM FORMATION. 



The Pulliam formation takes its name from the Pulliam ranch 

 on the Nueces river, where some of its ledges of soft sandstone are 

 known to contain from ten to thirteen percent of asphalt. This 

 formation is by some regarded as the attenuated eastern equiv- 

 alent of most of the Eagle Pass beds. It consists of clays and 

 marls, with some ledges of sandstone, limestone, and shell beds. 

 One of the sandstone ledges forms the divide between the upper 

 branches of Chaparrosa creek, and Mula and Palo Blanco creeks. 

 It is also exposed in places in the north half of block 3 south of 

 the Anacacho mountains. South of this it is covered by the Ter- 

 tiary deposits, which deepen to the south and east. The thickness 

 of the formation on the Nueces river has been estimated at from 

 100 to 200 feet. This clearly increases to the westward and along 

 the Chacon creek and south of the west end of the Anacacho 



