94 Gi "GEOLOGY. 
great distance from the mass of the mountain, which thus appears furrowed by rugged and pıe- 
cipitous cafions. Each spur, as far as examined, presented rocks similar to those already 
described, the trend also being northwest and southeast, and the dip about forty degrees. The 
rocks appeared in jagged points all over the mountain, and no soil or vegetation could be seen. 
Large beds of limestone were, however, observed, much thicker and more extensive than the 
exposures seen before. It rests in inclined beds, conformably with the gneiss or mica slate, and 
is belted or marked by bands and lines in the same direction. "Thin seams or veins of granite 
VIEW i pn ME THE DESERT. 
and of quartz were also seen in parallel layers. Crystallizations of hornblende and other 
minerals were observed at the line of junction of the beds with the granitic masses. This lime- 
stone is granular and crystalline, and is more or less blue, and is not as white and coarsely 
crystalline as the metamorphic limestones of New Jersey and New York. 
i COLORADO DESERT. 
The ground over which we passed was gravelly and sandy. The sand was coarse, for all the 
finer particles had been removed by the wind. A range of hills, at the base of the mountains 
on the left, distant about ten miles, appeared to be composed entirely of sand, its surface bein 
drifted into ridges. i 
Hot Spring.— After travelling about seven and a halt miles over these long and barren slopes; 
we saw a green spot in the distance, and soon came to two large springs of water rising in the 
bare plain, not far from the foot of the mountain. (See map.) One of these springs is warm, 
