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 bounding 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 

 ai^pearance 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 Bairbara ; 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) 



