163 
South of Hicks (see sheet 24, p. 178) hills of various kinds of rocks 
border both sides of the valley. To the west areridges consisting of 
beds of fragmental materials ejected from volcanoes, 
with some lava flows in their higher portions. The 
low ranges southeast of Hicks consist of granites and 
diorites, the former apparently in dikes penetrating 
the latter. South of milepost 15 are two prominent buttes of coarse- 
grained massive light-gray granite, 
Granite is exposed in a small cut on the railway near milepost 17, 
a few rods north of Wild siding, and a short distance farther west a 
small knoll of the same rock rises from the river flat just west of the 
tracks. At milepost 18 and for a mile and a half southwest of it 
there are cuts in gravels and sands which are part of the alluvial 
filling of the valley,. deposited long ago by Mohave River. Beds 
of fine-grained material cropping out at the base of these deposits 
are probably somewhat older still and mark another period of depo- 
sition by a stream flowing across the region. At milepost 20 is another 
small cut in dark granite which underlies the gravels along the east 
bank of the river. 
Kast of Helen siding a group of buttes and hills of moderate eleva- 
tion lie a short distance southeast of the railway. They consist of a 
peculiar fine-grained light-colored lava (rhyolite) intersected by some 
small masses of dark rowle (hornblende diorite), either in dikes or in- 
clusions. This lava extends several miles to the southeast in hills- 
and ridges of moderate height. Some portions of it are completely 
decomposed to white kaolin,! and material of this sort 4 miles east 
of Bryman is worked Extensively to supply “chalk”? works at Bry- 
man. The product, being of pure white color and very fine grain, 
is used for various purposes 
At Oro Grande (Spanish ion big gold) there is a large Portland 
cement plant. Here Mohave River contains water nearly all the 
year, and it is used for the irrigation of various crops 
THE SANTA FE ROUTE, 
Hicks. 
Elevation 2,278 feet. 
Kansas City 1,680 miles. 
Oro Grande. in a narrow strip of bottom land. East of the town 
Elevation 2,635 feet. is a high ridge consisting of granite, marble, schist, 
City t somites, 204 hard sandstone.? The marble is used in the manu- 
facture of cement at the plant in Oro Grande. It is 
quarried at several large openings half a mile east of the railway. 
‘This kaolin results from chemical 2 The structure of the ridge east of Oro 
changes due to weathering, in the course | Grande is complex, for the beds are bent 
of which feldspar, one of the component | and Mires and cut by great masses of 
minerals of the rhyolite, loses alkali by | granite (quartz cicienentss) which have 
through 
leaching, a bess proportion of claylike | been baad 1 limestone, shale, 
alumin’ and sandstone, the resulting heat and 
pressure altering these rocks to marble, 
mica schist, and quartzite. The high 
central and several lower ones con- 
sist of very hard quartzite, and the hills 
on the south side of the range are of 
granite. 
te being left behind, to- 
gether with more or less quartz and other 
minerals which are in the form of hard 
eae _ Alter thorough _mixing __ with 
brchestiarnne deposited in tanks, leav- 
ing the granular constituents behind. 
