LOWER CRETACEOUS FORMATIONS.
Scaphites ? sp., several small distorted specimens that may be Olcostephanus
or some other ammonoid genus. Turrilites brazoensis Roemer.
Nautilus texanus Shumard.
Del Rio Clays.
The top of the breaks of the Rio Grande to the northeast, east, and southeast of Del Rio is formed of the Buda limestone, to be dis cussed later. The slope is composed of the Del Rio clays. Within ,the breaks near Del Rio, to the southeast, is a conical-shaped butte, called Lone Hill, also composed of these clays, and they are exposed 20 miles west of Brackett, on the road to Del Rio, where they are over lain by the Buda limestone.
The following is a section exposed at the old 6cher mine 2 miles north of east of the Del Rio court-house:
Section <it ocher mine 2 miles north of east of Del Rio court-house.
In the lowest stratum are thin, sandy flags containing Equisetum?
and Nodosaria texana. Exogyra arietina is very abundant throughout the section. No. 4 is the bed from which the red ocher has been
mined. This ocher is usually a vermilion-colored clay.
The section above described illustrates the lithologic characters of
the beds. At the base, along the contact with the Fort Worth lime stone, there is a white calcareous clay. Above this bed the clays are usuall} T greenish before weathering. When subjected to atmospheric action they become yellowish. Beds of red clay occur near the top. Frequently the Exogyra arietina is cemented into slabs by a sandy ferruginous matrix. The thickness, as determined by the aneroid
barometer, is 100 feet.
Although fossils arc numerous in these clays, there are but few
species. The following are the species collected and the localities
n hence 1 they were obtained:
Fossils from 20 miles west of Brackett.
Nodosaria texana Conrad. Pecten, a small undescribed species.
Fossils from old ocher mine on bluffs miles north of east of Del Rio court-house.
Nodosaria texana Conrad. Exogyra arietina Roemer. Plicatula incongrua Conrad. Neithea sp., fragments. Esquisetum?
Bull. 104 -2
7. Buda limestone capping. Feet. 6. Slope to the edge of the bluff covered with Exogyra arielina, a few feet. 5. Yellowish clay 15
4. Red clay 5 3. Thin indurated sandy layer $ 2. Red clay 10 1. (Jreenish clays 30