382 E. T. DUMBLE — CRETACEOUS OF TEXAS AND MEXICO. 



The Exogyra arietina clays and shales have a thickness of 140 feet, and 

 are as fossiliferous as usual. They occur only near the Rio Grande. The 

 change from the clays, shales and flags, which constitute these beds, to 

 the massive and somewhat cherty Vola limestone, which overlies them, 

 is abrupt. The Vola has its usual color of creamy white flecked with 

 red, and has a thickness of 80 feet. In places it is almost a saccharoidal 

 marble, and is better developed here than anywhere that I have seen it, 

 except at Kent. Its characteristic fossil, Vola roemeri^ Hill, was found in 

 the bed of El Soro creek. 



The Finley- Eagle Mountains Section. — The section between Finlej^- and 

 the Eagle mountains gives the greatest thickness yet observed in the 

 Washita limestone. It is a region of long continued disturbance and 

 volcanic activity, and the entire section has not been found in any one 

 locality, so that the exact relations of some of the beds described are not 

 certain, though the section, as a whole, is approximately correct. Here, 

 too, is shown the greatest variability in the deposits, due to the oscilla- 

 tion of the sea-bottom. Toward the Eagle mountains the limestones are 

 somewhat marly and carry an abundant fauna, as shown by the collec- 

 tions of Mr W. H. Streeruwitz. Just south of Sierra Blanca are alter- 

 nating beds of sandstone and flags, with a thickness of over 4,000 feet, 

 Exogyra americana, Marcou, being the only fossil found by me. This is 

 the upper part of the division, and the lower rocks are probably overlain 

 by the later sediments which cover the flat lying between this and the 

 Caprina ridge north of it. In this lower portion, as exposed elsewhere, 

 is repeated the occurrence, noted on Devils river, of the Ca'prina above 

 what was formerly considered its culminating point in the top of the 

 Fredericksburg, but here it is accompanied by a number of Caprotina 

 forms. The rock-materials : sand, grits, conglomerates, limestones and 

 beds of gypsum still indicate the oscillating character of the sea-bottom. 



Around Eagle Flat station, and between that point and the Diabolo 

 mountains to the north, the limestones are very arenaceous, and are 

 capped with a sandstone which I have previously referred to the Dakota. 



Compa/risons with other Localities. — From the observations made it would 

 appear that certain fossils which occur at one horizon in the Colorado- 

 Red River section are found at entirely difl'erent horizons west of the 

 Pecos. One of these is Exogyra plexa, Crag. In AVilHamson county this 

 fossil is found in the base of the Washita limestone, if not in the Kiamitia 

 clay, and it is also found at about the same horizon on Duck creek, in 

 Grayson county, while in the Kent section it is more than 300 feet above 

 the base of the limestone and overlies fossils which are found above it in 

 the Colorado section. The recurrence of Caprina and Caprotina forms 

 has already been noted, and the persistence of these forms from the Glen 



