THE SANTA FE ROUTE, 159 
cone about 250 feet high, with a large, deep crater initssummit. This 
cone, which is usually called Mount Pisgah, is as fine an example of a 
recent volcanic outflow as can be seen anywhere. Some of its features 
are shown in Plate XL (p. 151). 
The mountains which rim the basin north and south of Pisgah siding 
consist mostly of granites, the thick mass of volcanic tuffs and lavas 
constituting the southeast end of the Cady Mountains northwest of 
Ludlow apparently having ended at a point northeast of Pisgah. 
From Pisgah to Troy, a distance of 12 miles, there is a down grade of 
368 feet into the basin. 
North and south of Hector there are low hills of Tertiary voleanic 
tuff. The western extension of the lava sheet from Mount Pisgah lies 
some distance south of Hector, but it is approached and crossed by 
the railway between Hector and Troy. 
At Troy siding the basin opens out westward into a broad flat 
that extends to Mohave River, about 7 miles to the north. The 
plain here is remarkably smooth, and it is covered in part by silt and 
in part by low sand dunes. In an area of considerable extent about 
Troy there is a large volume of fairly good water only a short distance 
below the surface, and it rises within 4 feet of the surface near the 
siding. On account of this supply a number of settlers have recently 
taken homesteads in this flat, expecting to pump the water for irriga- 
tion. At most places here the water does not carry very much salty 
material, for this part of the valley drains into Mohave River, and 
salts appear not to have accumulated in it. 
A short distance northeast of Troy is a range of low hills consisting 
of voleanic tuff and lavas (rhyolite and basalt), which bear off north- 
westward to Mohave River. These materials probably also underlie 
the flat, for they appear in a number of low knobs to the west, south, 
and southeast of Troy. The larger mountain mass, 5 miles south of 
Troy, however, consists of light-colored granite (quartz monzonite). 
A very thick deposit of bowlders and gravel lies against these granite 
slopes, constituting high hills of rounded form. In one area of 
considerable extent these gravel beds are surmounted by a flow of 
black lava (basalt) 1 which caps a high mesa clearly discernible south- 
southwest of Troy. 
1 
the level of the railway. A portion of the 
This lava came from a cinder cone at 
ite | northern rim of thisold valley in the higher 
high altitude behind the main grani 
ot 
range and flowed to the north and north- 
west down a valley of moderately steep 
slope. Its irregular termination 4 miles 
southwest of Troy is not very high above 
slopes 6 miles south-southwest of Troy has 
since been cut away by erosion, so that 
part of the black edge of the upper por- 
tion of the flow isnow visible from Troy. 
