156 GUIDEBOOK OF THE WESTERN UNITED STATES. 
South of Bagdad there is a desert plain 8 miles across, partly filled 
on the east with the lava sheet. West of this sheet the flat contains 
salty and gypsum-bearing deposits, mixed with more or less fine 
sand. ‘This is the west end of the basin which contains the salt and 
um east and south of Amboy but which, just west of Amboy, 
is floored with lava. On the south side of the basin rises a prominent 
ridge of voleanic rocks of supposed Tertiary age, consisting of agglom- 
erate and tuff associated with large bodies of light-colored lavas 
(latite and rhyolite). An old lead-silver mine in this range has pro- 
duced considerable high-grade ore from a vein that is exceptionally 
well exposed at the surface. Three miles farther south is the high 
range known as the Bullion Mountains, which consists of igneous 
rocks of various kinds. 
West of Bagdad the train begins to climb rapidly out of the basin 
along the slopes of cinder cones and masses of black lava (basalt) 
lying on older granitic rocks. Halfway between mileposts 672 and 
673 a small black hill south of the railway is evidently the remnant 
of a cone or larger mass of basalt. Near milepost 674 there is in view 
just north of the track a large cone made up of inclined beds of 
reddish cinder. 
Another similar cone is also visible a few miles farther northeast. 
As the train ascends the slope to the north it approaches hills and 
ridges of volcanic tuff and ash, overlain in places by flows of basalt. 
A mile south of milepost 678 several small, low black knobs rise out 
of the desert plain, probably the remnants of an old crater or a flow 
of lava (basalt), considerably eroded and buried by sand and gravel. 
West of Siberia siding the railway makes some long, sweeping horse- 
shoe curves in rising on the slope of the basin. These curves give 
fine views back into the wide basin, in which the cinder cone neat 
Amboy is a prominent feature. At Klondike siding (milepost 682) 
absorbed by plants is evaporated through 
their green surface. Most of the cactuses 
have leaves, but as a rule the leaves are 
minute or even microscopic, and the 
structure of their cells is such as to hinder 
transpiration and conserve the water 
stored. In the walls of the cells are thin 
sievelike places which permit the easy 
passage of water from one cell to another 
throughout the interior. A barrel cactus 
in cactuses is often palatable, but not in- 
variably so. It is interesting to note that 
those in which the water is nauseous are 
less protected by spines than those whose 
juice is sweet and tempting. In experi- 
menting with desert mice it was found 
that they will not drink water, a fact 
which suggests that they secure moisture 
from the plants they consume, or possibly 
they have a special means of separating 
moisture from the air. The spines of the 
cactus are straight or curved, hairy of 
feathery, and grouped in starry clusters 
or in rows. They have been used for 
fishhooks, needles, and combs and in va- 
tious other ingenious ways by the prim- 
itive tribes. The flowers of the cactus 
vary in form, and most of them are ex- 
tremely beautiful. The different species 
display brilliant tints of purple, yellow, 
orange, and rose. Some open by day; 
others by night. Many of the species 
bear edible fruits, and the seeds of some 
are used by the Indians for food. 
