FOSSIL PLANTS—POSUNCULA RIVER—TEJON. 37 
these transported fragments. Similar fossils were afterwards found, in place, near the summit 
of the Sierra Nevada, at the pass called the Canada de las Uvas.—(See chap. V!.) 
Posuncula, or Kern river is one of the most important streams that enters the Tulare valley. 
It isthe most southern of the tributaries to the Tulare lakes, and enters that now called Kern 
lake by a number of mouths. After the river emerges from the Tertiary hills, it turns abruptly 
from its westerly course to the southward, and spreads out over the slope by a number of shallow 
channels, which thus form a broad bottom land covered with timber and grass. 
It was evident that this river is liable to great floods, and that the current is at such times 
very rapid and powerful. The low bottom lands or banks were not very broad, but were thickly 
overgrown with cottonwood, sycamore, and willows of several kinds. 
The water of the river was perfectly clear, and at the ford the temperature was 67° ; but it 
must become more and more elevated as the water descends to lower parts of the stream in tlie 
plain, where it spreads out into the many sloughs, that are comparatively shallow, and expose 
large surfaces to the rays of the sun. A conglomerate of sand and gravel is exposed in the bed 
of the river, which resists the wear of the current exceedingly well. 
Terraces.—Indistinct terraces were observed on the southern bank; and the upper one forms 
the long, even outline, before referred to. From the top of this terrace the road descends 
gradually toward the south until the Tulare plain is reached. The soil for the greater part of 
the distance contains a large proportion of clay, and is exceedingly fine. "When broken up by 
the animals, it became perfectly light and dusty, and resembled dry ashes. This argillaceous 
and light character is principally confined to the lower parts of the slope and to the plain. The 
soil probably is not good or so well fitted for cultivation as the purely granitic soils found in 
the vicinity of the granitic and metamorphic rocks where the Tertiary strata are absent. 
We soon reached the foot of the slope ; or it became so gentle that we appeared to be travers- 
ing a wide plain. On the west the view towards the Tulare lakes was unobstructed, and on 
the east the mountains were formed of several ridges. High peaks were seen, but they. were 
without snow. 
The high ridge, or mountain, along the western base of which we travelled, appeared to be 
well timbered to its top, and no outcrops of rock were visible. We were, however, several 
miles distant, and the rocks may have been hid by the trees. "This ridge, as it extends to the 
south, decreases in altitude, and finally passes below the general level of the plain or moun- 
tain-slopes. Our course was directed to this point; and on turning it, a broad area, several 
miles in width, and nearly level, was brought to view. It extends back from the ridge, east- 
ward to the main chain of the mountains, and is enclosed on three sides, being a broad valley, 
or partly enclosed slope, called the Tejon. It is traversed by a creek issuing from a pass in the 
mountains, and this creek cuts through the southern point of the low ridge which separates the 
valley from the Tulare plains. 
The low, rounded hills of the Tertiary formation appear to skirt the Sierra Nevada southward 
from the cañon of Posuncula river to the extremity of this low ridge. At this extremity they are 
developed in a narrow belt of elevations, which in many places present vertical exposures that are 
white and chalk-like. They are probably a compound of white volcanic sands and ashes, and the 
debris of white granite. Near the entrance to the valley of the Tejon creek I found large accumu- 
lations of drift confusedly stratified, and obscuring the stratification and lithological characters 
of the Tertiary strata. This dxift is principally of syenite and coarsely crystallized granitic 
! See also a description and drawing by Professor J. W. Bailey, Appendix, Article V. 
