728 TRANS-PECOS TEXAS. 



alternating horizons that were laid down in a near shore oscillating bed, giv- 

 ing alternating bands of sandstone and siliceous shell brecciate limestone 

 through a range of sixty-five feet, when the littoral features pass and massive 

 foraminiferal limestone is reached, ending in a third Caprotina horizon with 

 Monopleura. 



Fifteen feet above the base of the Bluff bed the last horizon of Exogyra 

 texana appears in a finely comminuted siliceous shell limestone ten feet thick. 



The combined Foraminiferal ( Orbitolina texana), Caprotina, and Monopleura 

 horizons form the most extensive deep sea deposit observed in the whole 

 Cretaceous section in El Paso County. Their limestones occur in Bluff and 

 Yucca mesas, in massive perpendicular bluffs forty to eighty feet high. At 

 the east entrance of Quitman Pass the foraminiferal limestone is one hundred 

 feet thick. The foraminifera ranges from the base of the massive limestone 

 to the base of the Caprina horizon, near the top, but is more abundant near 

 the base, where it forms the mass of the rock with millions of individuals. 

 Just beneath the Caprotina horizon a narrow band of very large flat oysters 

 occurs. The fossil is eight to ten inches in length and very flat. On weath- 

 ering in the face of the bluff only sections and fragments could be obtained. 

 In Camp Mesa, near the upper edge of the alternating series of this bed, there 

 occurs a narrow horizon of Serpula (var. ind.) The fossil is an eighth of an 

 inch and less in diameter, and seems to be of considerable length. 



A part of Yucca bed, including the Orbitolina and Caprotina horizons, 

 rests along the west flank of Quitman Mountain between Big Spring Gulch 

 and Kyle's prospect, where it has been caught up between granite on the west 

 and porphyry on the east, and fused into granular marble. All fossils except 

 the most refractory have been destroyed. 



The Serpula, Orbitolina, and Caprotina horizons occur in the gulch on the 

 north, east, and south sides of Kyle's prospect, where they have been greatly 

 distorted and broken. This bed also appears in the hills one mile west of 

 Bluff Mesa. At the foot of the hill one mile northwest of Eagle Spring there 

 is a narrow band of siliceous limestone, with numerous individuals of Orbito- 

 lina texana, that is considered to belong to the Bluff bed. 



QUITMAN BED. 



In Quitman Mountain north of Quitman Pass the stratified rocks have, 

 with the exception of an occasional remnant, been removed from the body 

 of the mountain by erosion, leaving bare the granites and porphyries that 

 once formed the heart of the mountain. The stratified Cretaceous rocks, ex- 

 cept where concealed by basin debris, extend around the base of the moun- 

 tain, with their eroded edges projecting upward with the slope of the moun- 

 tain side. 



