106 GUIDEBOOK OF THE WESTERN UNITED STATES 
Paleozoic strata, with the underlying presCamiribn sandstones, 
limestones, and schists exposed to the south.” 
% The principal features cf the formations in this region are given in the 
following table: 
Formations in the Van Horn region 
Age Formation Character fee ey 
Cretaceous. Sandstone and limestone. 1, 800+ 
Limestone, mostly massive, light to dark, many 
Permian, reefs, ie anconformabty on older strata down 2, 800 
to pre-Cambrian.) 
Pennsylvanian. Limestone, massive, on dark shale. 800 
Devonian‘. Chert and dark slabby shale. 150 
Silurian. Fusselman. Dolomite, massive, light. 100-+ 
Montoya. pres Sg cherty, with basal brown sandstone 400 
Ordovician. 
El Paso. Limestone, massive, mottled, lower part sandy. 1, 000 
Sandstone, red arkose conglomerate lenses and 
Upper Cambrian. | Van Horn, — tae (Lies unconformably on pre-| 50-700 
Limestone, omrperit — banded with chert; a 
carries masses of Cryptoz 
Sandstone, red, in part areTiaceciin and conglom- 
Millican, eratic. 3, 000 
Genthereciake including schist fragmen 
Pre-Cambrian. ae sills of diabase and carries interbedded vie 
ne Schist and gneiss cut hy igneous rocks and veins of 
Carrizo Mountain, quartz and pegmatite, 
The pre-Cambrian schist constitutes | face of the pre-Cambrian rocks. It is 
the Carrizo Mountains, which lie be- | several hundred feet thick in the ridges 
tween the Texas & Pacific and South- | northwest of Van Horn, but it thins 
ern Pacific Railroads west of Van Horn. | out in places, together with the over- 
It is also exposed in a few small areas lying old - a a te) that the lime- 
in the adjacent region. The Millican | stone of Perm i 
formation, which contains much red 
shale and cherty limestone, resembles 
Apac stone lies directly on El Paso limestone, 
group of Arizona. It constitutes an | as shown in Plate 15, A. In places the 
area of foothills northwest of Van Horn. | Van Horn beds, especially the lower 
4 uy oubtedly it is younger ones, consist largely of coarse material 
f : 
Flat station on the Texas & Pacific | co ter sediments. Much of 
Railway, where the limestone of Per- | the Van Horn material is of red color 
mian age overlaps bo The presen The succession of El Paso to Fussel 
pa fragments i ae limestone whic 
of metamorphi 
of the Millican beds indicate that they | hills about the 
pene a than the schists, doubtless 
