26 W. P. Jenney—Notes on the Geology of Western Texas. 
caleareous sandstone full of the borings in pairs of the Scolithus 
linearis of the Potsdam sandstone. The total thickness of this 
bed is about 250 feet. 
C. Gray ceynatitce limestone, nearly 250 feet in thickness, 
hg yi conformably on the sandstone: in the lower part of the 
ed no fossils were found, but in the upper layers one or two 
sien allied to Archeocyathus are abun ant, which indicate its 
equivalence with the Calciferous sandrock. 'A few feet of sand- 
_ oe dark red separates this bed from the next in 
the s 
D. Ges magnesian limestone, about 450 feet in thickness, 
and containing much flint or hornstone ; its — fos- 
sils are a oe ana shells allied to Orthoceras an 
Helicotoma. On more extended arichinahices! this bed may be 
identified as Chazy. 
black limestone, nearly 100 feet in — forming 
the crest of the range: it rests conformably on bed D, and the 
contact is very distinctly marked. The black ‘Teesuee is filled 
with well. known fossils of the Trenton period, including Maclu- 
rea magna, species of Orthis, Orthoceras, Cyrtoceras, and corals 
allied to Halysites and Syringopora. 
Passing over the top of the mountain and descending on the 
western slope, the next stratum in the series encountered rests 
on the Trenton limestone ; but it contains forms of life which 
are totally different though no less abundant. 
Gray limestone, which has been very much denuded, yet 
es less than 200 feet in thickness remains; in the lower part 
of the bed Halysites gracilis, species of Syringopora, Zaphren- 
tis and several other corals, together with -ehynchonella increbes- 
cens were found, and in the upper part a varieties of Bra- 
chiopods, among which were Strophom gosa, species of 
Leptena and several of Orthis, which identify 3 4 with the Hud- 
son period. 
G. A coarse conglomerate, composed of rounded and angular 
fragments of the Trenton an udson limestones cement 
together by carbonate of lime and sand: it is of varying thick- 
ness, being i in some places 60 feet thick and in others entirely 
wanting in the series. It rests unconformably on both the 
Trenton and Hudson beds, and seems to contain no fossils; but 
from its position it may possibly be equivalent to the Oneida 
conglomerate of New York 
H. A ridge of light gray ‘erystalline limestone extends along 
the western base, parallel to the crest of the range, and rests 
SS on the conglomerate and the Trenton and Hud- 
ts thickness is about 400 feet, and the dip is — 10° 
to the rae ‘These facts show that it was deposi r a 
partial uplifting of the underlying beds, and that eaatesquently 
