164 GUIDEBOOK OF THE WESTERN UNITED STATES. 
The plant also uses a small amount of schist and the decomposing 
granite. These rocks are ground, mixed in proper proportions, and 
melted into a clinker, which, when pulverized finely, forms Portland 
cement. Portions of the marble are so nearly pure calcium carbonate 
that they are suitable for calcining into lime for use in beet-sugar 
manufacture, and a large amount of it has been obtained for that 
purpose from quarries about a mile east of Oro Grande. 
Granite extends west to the river bank and railway half a mile 
beyond milepost 32, or nearly a mile beyond Oro Grande. At the 
railway bridge across Mohave River at milepost 34 it constitutes 
the walls of a canyon through which the river flows for 2 miles. In 
slopes east of the bridge are conspicuous exposures of the granite 
cropping out in bare ledges, appearing like a great pile of huge 
bowlders and slabs. This rock is quarried extensively for building 
stone at several places southeast of Oro Grande. It is a handsome 
and durable material, easy to dress, and uniform in color. 
For several miles beyond milepost 34 the railway follows the foot 
of a high bank of sand and gravel, much of it in regular, horizontal 
layers. This material constitutes a flat-topped river terrace; it was 
deposited by Mohave River at an earlier stage of the development of 
the valley and of the terrace plain, which extends far to the west. 
The sand and gravel continue along the west side of the track for 
‘several miles, but the best exposures of the beds are near milepost 36. 
Across the river east of this place are numerous rocky ridges ending 
in a small knob near the river. These ridges consist mostly of gran- 
ite, but some of the more distant ones include also large masses of 
white and variegated marbles which have been quarried for building 
stone. 
Victorville is an old settlement that has grown gradually as head- 
quarters for mining, quarrying, and ranch interests in the surround- 
ingregion. Above and below the town there are many 
Victorville. ranches that use the river water for irrigation. A 
—— 2,716 feet. short distance south of Victorville the river passes 
opulation Le : : 
KansasCity 1,704miles, -hTough a short narrow canyon of the granite, with 
walls about 150 feet high. The railway is built 
on the west bank of the river, partly on an embankment and 
partly on a shelf cut in therock. The canyon is due to a project- 
ing ridge of the granitic rock which slopes down abruptly under 
the great sheet of sand and gravel which underlies the wide 
plain extending far to the west. The canyon is a gateway t0 
a wide valley bottom with numerous ranches. Possibly some 
time a dam will be built in the canyon to create a storage reser- 
voir that will extend some distance up the valley. Although the 
flow of the Mohave in the dry season appears small, a large amount of 
water passes through this gap in a year, and heavy freshets some- 
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