CONTENTS. 
9 
CHAPTER XVII. 
Of the Quaternary period in California. 
Observations on the condition of California, from, the time of the deposition of the blue clay downwards.—Removal of the 
upper local drift of the Pacific slope, its persistence in the Basin and region east of the Sierra Nevada.—Ancient terraces.— 
Height of the waters of that period.—Detailed notice of the terraces on the Salinas and San Bonito.—Santa Margarita.— 
Terraces of Santa Maria valley, Panza valley, and Carizo.—Terrace levels of Santa Inez valley.—Terrace along Santa 
Barbara shore.—Terraces of Los Angeles valley.—Synopsis of localities of terraces, with their altitudes.—Upraised beaches 
of San Luis Obispo.—At San Pedro.—Section of cliff along shore.—Recent shells in. 
CHAPTER XVIII. 
Geology of the district from San Diego to Fort Yuma. 
Tertiaries of San Diego.—Volcanic rocks near San Pasquale.— San Ysabel.—Axis of the Cordilleras.—Warner’s ranche.— 
Agua Caliente.—Minerals in the granites of San Felipe.—Springs of. —Porphyritic rocks between San Felipe and Vallecitas. — 
Springs at latter place.—The Cordilleras.—Their breadth,, altitude, and structure.—Volcanic intrusions in.—Included 
gneiss.—Probable age of the range.—The Colorado Desert.—Tertiaries and alluvium.—Curved beds.—Excessive tempe¬ 
rature.—Physical appearance of the margin.—Sackett’s wells, soil at water of.—Igneous rocks of Desert.—Lagoons.— 
Alamo Mocho.—Wells at, and supply of water.—Slope of the Desert.—Its vegetation.—Climatal phenomena.—Trail to 
Cook’s well.—Drift sands.—On New river, and the present fluviatile action of the Colorado.—Algodones.—Colorado river.— 
Fort Yuma —Of the climate and water supply of the Desert. 
CHAPTER XIX. 
Fort Yuma to the Fimas villages. 
Fort Yuma.—Colorado.—Ancient terrace and river bed.—Aspect of Gila river near its mouth.—Occasional overflows.—Vege¬ 
tation of river bottom.—Soil, limits, and constitution of the Sonora Desert.—Big Horn Mountains.—Geology of.—Native 
copper ore.—Remarks on—Basalt overflow, its great extent.—Pimas journada, geological structure of —Granitic axis.— 
Quartz veins.—Titanium ore.—Plain at the Maricopas wells.—Water of.—Influence of subterranean springs upon vege¬ 
tation.—Pimas villages.—Cultivated lands.—Character of the soil.—Necessity of irrigation.—Recapitulation. 
CHAPTER XX. 
Canons of the Gila river and Pinaleho mountains. 
Basalt overflow east of the Pimas villages.—Physical appearance and topography of the canons.—Trend of the hills 
ranges.—Saddle mountains.—Breadth of the primary rock.—Elevation of the sedimentary beds, eastward.—Subsequent 
alterations of level.—Plutonic forces.—Aggregate of igneous rocks.—Spire hills, their structure.—Basalt dykes.—Meta- 
morphic sandstone.—Its lithological character and geological age.—San Pedro river.—Its course —Fertile valley, gypseous 
beds of.—Denudation, thickness, position, variety, and probable age of.—Conglomerate of the upper part of the valley.— 
Thickness, position.—Auriferous gravel. 
CHAPTER XXI. 
District of Play as, or small valley troughs. 
Ascent of the spurs of Sierra Calitro.—Approach to the Playa.—Deposit of conglomerates.—Granitic axis.—Stratified rocks 
on west side of the Playa.—Extent, surface, and boundaries of the Plaja.—Sand ridges of the margin, their origin.— 
Palaeozoic rocks of the Basin.—Volcanic rocks, serpentine and augite.—Thickness and dip of the encrinal limestone — 
The Playa in the rainy season, its physiognomy.—Chiricahui mountains, structure and trend of.—Its relation to the Pina- 
leno mountains.—Structure of Puerto del Dado.'—Porphyry dykes.—Dos Cabezos.—Volcanic rocks in canon.—Valle del 
Sauz, limestone rock of.—Extent of valley.—Peloncillo hills.—Trachyte and basalt overflows.—Extension northward.—■ 
Successive eruptions.—-Pyramid hills, their structure.—Valle de los Playas, soil and sandstone of. 
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