94 
ESTERO VALLEY-PANZA HILLS. 
stream. This elevated rolling plain stretches several miles to the east, when it drops down 
into Tulare valley. This lofty district owes its elevation to Gavilan range coming in at this 
point in its southern course, and intermingling its strata with those of San Jose. The result of 
this union of two parallel ranges not only produces the highly elevated country, hut perhaps 
also the increased elevation of the San Jose range itself, which at this point (the head of Carrizo 
creek) sustains a loftier crest than elsewhere in its course. South of this point the two ranges 
separate and pursue different courses, forming, by their divergence, Estero plain, a wide trough 
plain, with a gentle descent to the south-southeast, where it opens into Tulare valley by the 
subsidence of the Monte Diablo range at the extreme south. 
Estero plain is a miniature of Tulare. The hills hounding it on either side supply it with 
water, small in quantity, which collects in lagoons or ponds in the centre, and thence flows 
sluggishly south, forming the Agua de Paleta, which rolls into Buena Vista lake, in Tulare 
valley. The northern edge of the plain near Carrizo and Panza hills furnish the largest amount 
of water, as many as three distinct streams being observed to roll down to the lake in the 
centre of the plain, which is uninhabited by man, and occupied only by herds of deer, antelope, 
and wild horses, with which it abounds. It* is about forty miles long, and averages twelve 
broad. Nothing exact is known of the geology of this plain. Its geography was compre¬ 
hended exactly by looking from the summit of Panza hill, which overlooked the whole country 
south and east as far as the eye could reach. The southern portion of the plain was again 
observed in crossing from Tulare to Cuyama plain ; of its structure nothing more is known than 
that its eastern ridge is the Monte Diablo range, terminating south at the head of Tulare 
plain—its western the San Jose range ; the sandstones slope into Estero from either side. Two 
slight elevations cross the plain above and below the lake, as if a dyke crossed in these places. 
The plain itself was not entered. 
In treating of the San Jose mountain range, allusion was made to the axial and sedimentary 
rocks; the textural character, dip, and thickness of the strata on its eastern side are there 
given, and need not again be repeated. Hornblendic gneiss appears here upon the east side 
of the range along the bed of Carrizo creek for some miles down below its source ; it presented 
the appearance of a stratified rock dipping away to the northeast. Although the granitic rock 
was exposed at a few points east of the range, yet nowhere was the gneiss rock observed in 
contact with it there. Panza hills are sandstones, elevated by felspathic granite, which occu¬ 
pies low bosses on the southeastern edge of the hills, and have no gneissose rock nor any 
appearance of the limestones found at Gavilan ; the point of contact of the sedimentary and 
upheaving rocks was not, however, observed; the lowest rock was a series of brown sandstones, 
with sharp angular outlines, and serrated and triangular shaped crests, in every respect similar 
to the lower beds of the Santa Inez chain at Santa Barbara ; above these were coarse conglom¬ 
erates and grits with saline (gypseous) veins, and thin layers of limonite. These represent 
the beds on the east of Santa Margarita valley, immediately below the ostrea and scutella beds; 
these also line the Santa Lucia mountains; then follow fine-grained sandstones with ostrea 
and pecten; and, finally, where the hill drops down to the creek bottom, fine arenaceous clay 
beds consolidated, containing area obispoana. Both the northern and southern Panza hills 
have a similar structure, and dip southwest from 25° to 35°. The total thickness of these 
beds approached eleven hundred feet; the dip is towards the San Jose range, from which it is 
separated by the valley intervening ; this valley, (Panza) like that of Santa Maria, is also one 
of denudation, presenting terraces one hundred feet high on the east side of the San Jose range, 
