52 
GEOLOGY. 
the summit; but beds of a bard, compact, and slaty rock, composed chiefly of hornblende and 
black mica, were found to alternate with it. One of these hard beds greatly resembled a trap- 
pean rock, being black and very dense. Veins of carbonate of lime were found traversing it 
irregularly, looking as if they had been intruded. The mineral was not lining fissures, but 
formed a part of the rock. Ridges of white limestone were found in the vicinity. 
The slope of the Basin is a broad, gently inclined plain, reaching out with a nearly uniform 
descent for several miles without any obstruction. The creek flowing out from the ravine of 
the pass on the east side has cut a long valley in this slope, extending for several miles below 
its general surface. We travelled in this valley ; and the view on each side was bounded by 
banks, of nearly uniform elevation, looking like terraces. These banks were from fifty to one 
hundred feet high, the elevation decreasing towards the lower part of the valley. The width 
of the valley varies from one-eighth of a mile, or less, to half a mile. Occasional exposures of 
horizontal or gently inclining strata could be seen, but they were much obscured by the talus 
and earth broken from the sides and forming a slope to the bank. No satisfactory section could 
be made, nor even the lithological characters of the beds determined. The upper portions of 
the slope are undoubtedly formed of loose and irregularly stratified sand and gravel, derived 
from the elevated ridges and canons of the mountains, and spread out upon the slope as if they 
had been laid down under the sea, or were formed by its action into a broad, gently shelving 
beach. 
It is probable that Tertiary strata are exposed along this channel in the slope, but I did not 
succeed in finding any organic remains indicative of the age of the strata. The vegetation in 
the valley was remarkable and extraordinary in its appearance, consisting entirely of the 
straight trunks of the yucca, which grew very thickly in several places, and at a distance looked 
like bands of Indians. The leaves are about as strong and sharp as a bayonet, and it is com¬ 
monly called the bayonet tree. A view of the valley and these yucca trees is given in Chapter 
XVI, View XI. By ascending from the bed of the little creek to the top of the banks border¬ 
ing the valley, it was found that the channel was merely a groove, if it may be so called, in 
the broad slope of the Basin, and on receding from it for a short distance it became invisible, 
and its existence would not be suspected ; the country seemed an unbroken plain. 
Several miles towards the north, hills of horizontal strata of clay and sand were visible, and 
they looked like the formation along Ocoya creek. These hills are near the entrance to Tah-ee- 
chay-pah Pass, and they are probably Tertiary. 
Lost Mountains .—The ridges and mountains which were visible from the summit of the Tejon, 
and which diversify the surface of the Basin, do not appear to form continuous ranges, but are 
isolated, standing apart, and separated by broad slopes. The nearest hill of this description 
appeared to be about ten miles distant, and we travelled towards it. The surface of the plain 
was gravelly and not covered by grass, but here and there an isolated and dried tuft called 
“bunch grass” could be found, and was much desired by the mules. A great variety of thorny 
shrubs was also found, and yuccas standing alone at intervals gave a peculiar aspect to the 
scene. 
The peculiarly arid and desert-like surface gave us little reason to expect to find springs of 
water, and yet it was reported by the Indians that they could be found about the lost mountains. 
After travelling about eight miles north-east from the foot-hills of the Sierra at the Tejon, the 
surface became gently undulating, and a green spot could be seen about a mile from the base 
of the first lost mountain. This proved to be a fine spring, surrounded by a thick growth of 
