v -\n; han.] EOCENE FORMATIONS. 53 
Section of bluff next lower down on the west side of th Frio f fiver. 
Feet. 
5. Coarse-grained brown ferruginous sandstone 20 
a. Soft white or yellowish sand 8 
1. Clay seam, with thin streak of lignite 7 
3. Soft white sands, sandy clay at base 20 
2. Sandy shale . 2 
1. White sandy clay 3 
Total 60 
The total thickness of the Eocene in the Uvalde quadrangle is prob- 
ably about 850 feet. 
CONCLUSIONS REGARDING THE EOCENE. 
From the foregoing discussion of the Eocene-Cretaceous contact, 
ind from the sections of the Eocene, it has already been made evident 
kit 
)t/k 
Fig. 5. — Weathering of the Carrizo sandstone at Chnpadero ranch. 
that there is not yet sufficient data to trace accurately the boundary 
between the Cretaceous and the Eocene. This boundary crosses the 
Rio Grande some miles, at least 4 or 5, above the north line of Webb 
County; it runs northeastward 1 or 2 miles northwest of India ranch, 
and passes some 1G miles west of Carrizo Springs. From here the 
boundary continues northeastward, and crosses the Nueces River about 
the north line of Zavalla County. It continues north of east to the 
Frio River, crossing that stream 2 miles below the Engelmann ranch, 
and 5 miles, in a straight line, north of the south line of Uvalde County. 
The last-mentioned point is the only absolutely determined contact. 
The others are supposed or inferred from the data at hand. 
The whole Eocene strata are sandstones, varying in hardness, coarse- 
ness of grain, and amount of contained argillaceous material, and clays. 
varying in the amount of contained arenaceous material and often con- 
