DESCRIPTION OF THE PLATES. 
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A, represents the Sierra Susanna having a trappean axis ; t, on which repose the red and 
brown sandstones, similar to those of the Cordilleras and at Buenaventura. 
B, the Sierra Monica with its amygdaloid and trachytic axes, t, t, uplifting ; d, e, /, the beds 
containing Lutraria, Natica , Cyclas , &c. 
j 7 ,'the granitic mass of San Emilio, through which the Peyrou canons. The sandstones h 
on its slope are the same as those of the Susanna hills. 
Fig. 6.—A more extended section, taken further north than the preceding ; a, view of the ter¬ 
raced hills along the San Buenaventura river ; b, amygdaloid upheave with asphalt; 
c, sandstones of Matilihah similar to Santa Barbara beds ; d, trachyte and asphalte of 
Matilihah ; /, lofty mountain in Santa Lucia range ; h, Santa Maria valley ; g, granitoid 
rocks of San Emilio ; i, sandstones of Cestek ; h , granite of Canada de las Uvas. 
PLATE V. 
Fig. 1.—Section from the ocean to the Sierra Nevada, across San Luis Obispo county, cutting 
across Santa Lucia, San Jose, and Gavilan ranges. 
a. Asphaltic veins passing up through the bituminous group of San Luis valley ; the strata 
elevated by upheaves of volcanic rock at t, t. 
't. The volcanic axis of Santa Lucia with the conformable sandstones g , g '. g", the granite of 
San Jose, Monte Diablo, and Sierra Nevada. The sandstones are more recent the more 
westerly they lie. 
Fig. 2.—Section in Santa Barbara county, from the Santa Clara river south to Camp 39 near 
Eanche Triompho. 
a, a, a. Amygdaloidal trachyte, with chalcedony; t , augitictrap; b, the red and brown sand¬ 
stones of San Buenaventura; c, d, e , sandstones of the Monica group, containing Lutraria, 
Cyclas , &c. Semee plain is almost wholly of volcanic rock. 
Fig. 3.—Section across the plains of Los Angeles and San Fernando to the Cordilleras, showing 
the deep beds of alluvium, f, on the plains ; a, veins of asphalt near Los Angeles ; b, 
intruding volcanic rock; c, strata of the San Luis group, almost vertical, or dipping 
north; d, strata of San Pedro ; e, sandstones of the Cordilleras continuous with the 
Susanna sandstones. 
Fig. 4.—Section of cliff at San Pedro, north of the custom-house; a , alluvium, 8 to 12 feet 
thick ; b, raised beach with recent shells, 4 feet thick ; c, argillaceous schist, 6 feet ; d, 
yellow clay beds and blue clay, with their stratified beds between, 30 feet. 
Fig. 5.—Plan of the junction of the Colorado and Gila rivers as at present, with the probable 
former course indicated by the dotted lines. 
PLATE VI. 
This plate is confined to the representation of the strata along the Mojave valley, and to a 
section of the Cordilleras through Cajon pass. In fig. 1 the mass of Kikal Mungo is not 
displayed so that the beds in the pass may be recognized. In fig. 3 it is restored, but 
the lower portion of the pass is obscured. 
Fig. 1.—Section through the Cajon pass. 
a, a, a, mica slate ; b, crystalline felspar rock ; c, talcose slates ; d , hornblendic gneiss ; e, 
pink sandstones, easily worn into rounded prominences ; f, f, f, incoherent sandstone 
beds, lying with a gentle slope to the northeast; g, g, axial granitic rocks. 
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