GEOLOGY OF THE REGION. 13 
paleontological studies are based therefore includes, with the excep- 
ion of three or four mislaid specimens, all of the marine fossils that 
lave hitherto been collected in Texas from rocks of the Malone 
formation. 
GEOLOGY OF THE REGION. 
All of the fossils described in this paper are from Malone Moun- 
tain and neighboring hills, and from within a few miles of the rail- 
way stations of Malone and Finlay. The greater number were 
)btained from east of the mountain, in the range of low hills which, 
n my article on " Discovery of marine Jurassic rocks in southwestern 
Texas," I called the Malone Hills. 
Beginning about half a mile north of Malone station, and in part 
,00 low to be indicated by the contour lines, with 50-foot intervals, 
Iised in the general topographic map of this region, these hills extend, 
rending at first about eastward and later more southeasterly, as a 
practically continuous Jurassic outcrop through the Neocene, for a 
istance of a mile and a half. At a mile to nearly a mile and a half 
rom the station they include a line of three connected hills (6 r , D, 
net E, on PL I, in order of distance from the station), which may 
e called. the Trio. As best observed on the southeastern quarter of 
ill E, the Trio geological section comprises three natural subdivi- 
ions, the lower, middle, and upper of which respectively may be 
esignated as Theta, Iota, and Kappa. 
The Theta subdivision of this section consists chiefly of sandstone, 
rith occasional courses of more or less sandy varying to relatively 
lire indurated limestone and some clay. The sandstone and clays 
re of a gray and yellowish-brown color, sometimes varying to pur- 
le and red. The purer of the limestone layers have a bluish-black 
olor, weathering to gray or brown. Bedded and irregular seams of 
hite cleavable calcite, sometimes several inches thick, here traverse 
Theta in its upper part. The base of the Theta is not exposed. 
I A short distance southeast of hill E is a very low truncate mound 
), from which the Kappa subdivision had been removed by erosion 
fore the prevalence of the Neocene waters which have so widely 
antled the lower levels of this region with tufaceous cements and 
mglomerates. The mound is gently synclinal in structure and con- 
sts of a few feet of Iota conglomerates rising rather abruptly from 
en tie basal slopes. A Theta outcrop of only a few acres, lying chiefly 
1 the interval between hill E and the Truncate mound, but extending 
so around the latter except on its east to southeast quarter, and 
nbracing so much of the basal slopes of both elevations as has been 
nuded of its Neocene mantle, is by far the richest collecting 
round in the Malone district. This interval is of anticlinal struc- 
ire, the strata increasing their clip from either the neighboring base 
cf< 
