Geological Survey Bulletin 613 Guidebook of the Western United States: Part C. The Santa Fe Route

South of Hicks (see sheet 24, p. 178) hills of various kinds of rocks border both sides of the valley. To the west are ridges consisting of beds of fragmental materials ejected from volcanoes, with some lava flows in their higher portions. The low ranges southeast of Hicks consist of granites and diorites, the former apparently in dikes penetrating the latter. South of milepost 15 are two prominent buttes of coarse-grained massive light-gray granite.

Granite is exposed in a small cut on the railway near milepost 17, a few rods north of Wild siding, and a short distance farther west a small knoll of the same rock rises from the river flat just west of the tracks. At milepost 18 and for a mile and a half southwest of it there are cuts in gravels and sands which are part of the alluvial filling of the valley, deposited long ago by Mohave River. Beds of fine-grained material cropping out at the base of these deposits are probably somewhat older still and mark another period of deposition by a stream flowing across the region. At milepost 20 is another small cut in dark granite which underlies the gravels along the east bank of the river.

SHEET No. 24 (click on image for an enlargement in a new window)

East of Helen siding a group of buttes and hills of moderate elevation lie a short distance southeast of the railway. They consist of a peculiar fine-grained light-colored lava (rhyolite) intersected by some small masses of dark rock (hornblende diorite), either in dikes or inclusions. This lava extends several miles to the southeast in hills and ridges of moderate height. Some portions of it are completely decomposed to white kaolin,¹ and material of this sort 4 miles east of Bryman is worked extensively to supply "chalk" works at Bryman. The product, being of pure white color and very fine grain, is used for various purposes.

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¹This kaolin results from chemical changes due to weathering, in the course of which feldspar, one of the component minerals of the rhyolite, loses alkali by leaching, a large proportion of claylike aluminum silicate being left behind, together with more or less quartz and other minerals which are in the form of hard grains. After thorough mixing with water, the fine aluminum silicate or kaolin is floated off and deposited in tanks, leaving the granular constituents behind.

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At Oro Grande (Spanish for big gold) there is a large Portland cement plant. Here Mohave River contains water nearly all the year, and it is used for the irrigation of various crops in a narrow strip of bottom land. East of the town is a high ridge consisting of granite, marble, schist, and hard sandstone.² The marble is used in the manufacture of cement at the plant in Oro Grande. It is quarried at several, large openings half a mile east of the railway. The plant also uses a small amount of schist and the decomposing granite. These rocks are ground, mixed in proper proportions, and melted into a clinker, which, when pulverized finely, forms Portland cement. Portions of the marble are so nearly pure calcium carbonate that they are suitable for calcining into lime for use in beet-sugar manufacture, and a large amount of it has been obtained for that purpose from quarries about a mile east of Oro Grande.

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²The structure of the ridge east of Oro Grande is complex, for the beds are bent and broken and cut by great masses of granite (quartz monzonite) which have been intruded through limestone, shale, and sandstone, the resulting heat and pressure altering these rocks to marble, mica schist, and quartzite. The high central peak and several lower ones consist of very hard quartzite, and the hills on the south side of the range are of granite.

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Granite extends west to the river bank and railway half a mile beyond milepost 32, or nearly a mile beyond Oro Grande. At the railway bridge across Mohave River at milepost 34 it constitutes the walls of a canyon through which the river flows for 2 miles. In slopes east of the bridge are conspicuous exposures of the granite cropping out in bare ledges, appearing like a great pile of huge bowlders and slabs. This rock is quarried extensively for building stone at several places southeast of Oro Grande. It is a handsome and durable material, easy to dress, and uniform in color.

For several miles beyond milepost 34 the railway follows the foot of a high bank of sand and gravel, much of it in regular, horizontal layers. This material constitutes a flat-topped river terrace; it was deposited by Mohave River at an earlier stage of the development of the valley and of the terrace plain, which extends far to the west. The sand and gravel continue along the west side of the track for several miles, but the best exposures of the beds are near milepost 36. Across the river east of this place are numerous rocky ridges ending in a small knob near the river. These ridges consist mostly of granite, but some of the more distant ones include also large masses of white and variegated marbles which have been quarried for building stone.

Victorville is an old settlement that has grown gradually as headquarters for mining, quarrying, and ranch interests in the surrounding region. Above and below the town there are many ranches that use the river water for irrigation. A short distance south of Victorville the river passes through a short narrow canyon of the granite, with walls about 150 feet high. The railway is built on the west bank of the river, partly on an embankment and partly on a shelf cut in the rock. The canyon is due to a projecting ridge of the granitic rock which slopes down abruptly under the great sheet of sand and gravel which underlies the wide plain extending far to the west. The canyon is a gateway to a wide valley bottom with numerous ranches. Possibly some time a dam will be built in the canyon to create a storage reservoir that will extend some distance up the valley. Although the flow of the Mohave in the dry season appears small, a large amount of water passes through this gap in a year, and heavy freshets sometimes occur. For several years the United States Geological Survey gaged the flow in the gap and the stream was found to have an annual volume of 68,000 acre-feet, or a mean of 95 cubic feet a second. One freshet carried 13,400 cubic feet a second but was not of long duration. The water of Mohave River is now used for irrigating about 15,000 acres, mostly in alfalfa, grain, and garden truck.

At milepost 39, 2 miles south of Victorville, the train leaves the bank of Mohave River and, entering a small valley, begins to climb the steeper part of the long ascent of about 1,000 feet toward the high mountain ranges which lie between the Mohave Valley and the coastal region of southwestern California. The course of the railway continues nearly due south. The slope, which is the southern edge of the Mohave Desert, consists of a thick succession of sheets of gravel and sand which extend far up the mountain sides and beyond the summit at Cajon (cah-hone') Pass. Near milepost 42 the railway has risen above the bottom lands of the Mohave Valley, and from this point southwestward for 10 miles or more there are fine views of the great mountain ranges ahead. To the southeast and south, across the upper Mohave Valley, rise the San Bernardino Mountains; the ranges ahead and to the southwest are the San Gabriel Mountains. These two ranges come near together at Cajon Pass, which leads into a gap between them. Mohave River and many other streams deposited the sand and gravel of which the plain is built, but later they have cut deep valleys across it. The relations of this detrital deposit are shown in figure 39.

FIGURE 39.—Section through sand and gravel deposits of the sloping plain along the Santa Fe Railway north of the San Gabriel Mountains, near Victorville, Cal.

A peculiar yucca, locally known as the Joshua tree (Yucca or Clistoyucca arborescens) is conspicuous on the grade up the mountains. (See Pl. XLI, A, p. 168.) It begins with a few scattered trees below Victorville and becomes very abundant in the region about Hesperia and the slopes above, nearly to Cajon Pass, its upper limit being closely determined by the altitude and temperature. It is said that attempts have been made to utilize the fibrous trunk of the yucca for manufacturing paper, but the tree is now used chiefly in making souvenirs and trinkets.

PLATE XLI.—A (top), JOSHUA TREE. A characteristic desert plant on the grade from Victorville to Cajon Pass, Cal. B (bottom), SAN GABRIEL MISSION, CAL. Founded by Padres Cambon and Somera under the direction of Fray Junípero Serra September 8, 1771. Photograph furnished by Santa Fe Railway Co.

Hesperia is a small village that forms a trade center for ranches along Mohave River a few miles to the east and several ranches and orchards near by cultivated by irrigation. There are two of these irrigated orchards just southwest of the village, and another a mile farther south, on the west side of the railway. Some grain is also grown on the adjoining plain. Considerable water, which is being used for irrigation, is obtained from wells 500 to 800 feet deep. Near Hesperia the creosote bush gives place to the Joshua tree and other plants suited to the higher altitudes. Between Hesperia and Summit there are many cuts in the thick body of gravel and sand constituting the great sloping plain.¹

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¹Near mileposts 50 and 52, where the railway ascends along the side of a small valley, the cuts are 30 feet deep and the gravels and sands are well exposed. Between mileposts 52 and 54 some of the gravel is consolidated into a loose conglomerate and the beds show a slight dip to the south, steeper than the upgrade of the plain. This feature indicates that there has been tilting of the crust of the earth in this region since the material was deposited. Near the mountains this dip is noticeable in many of the exposures. Between mileposts 55 and 56 there are some deep cuts in fine sand of buff color, with scattered beds and streaks of gravel.

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The traveler will note as he ascends the slopes that the bushes which are so widely scattered on the desert to the east and north become thicker and larger, and several new plants appear, notably the manzanita,² one of the most beautiful of the highland bushes, which forms a thick growth on the higher mountain slopes of this part of southern California. A far western variety of juniper (Juniperus californica utahenis) is also present, together with a peculiar piñnon (Pinus monophylla) differing from the Arizona tree by bearing larger nuts and a single leaf. Its nuts have been an important food product for the Indians. The beautiful Yucca whipplei is conspicuous, with its straight stalks which in the early summer bear a great cluster of white flowers.

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²The manzanita (Arctostcphylos patula) is a shrub having a smooth bark of rich chocolate color, small pale-green roundish leaves, and berries that resemble diminutive apples. It is this resemblance that gives the shrub its common name, Spanish for little apple, by which it is known everywhere on the Pacific coast. Bears are very fond of these berries. The manzanita covers many of the hills in California with a stiff, almost impenetrable growth. Its wood is hard, and the blaze from an old gnarled root cheers many a western fireplace.

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At Summit the railway reaches the top of the grade necessary to carry it through Cajon Pass, but the actual divide is in a cut a short distance west of the station. Cajon Pass is the great gap through the mountain barrier between the desert and the San Bernardino Valley, a gap occupied and drained by Cajon Creek and its tributaries. The train enters the pass proper as it descends from the divide on the edge of the desert into the valley of Cajon Creek. Beyond the summit cut the traveler gets a view of the deep valley of this creek, which crosses the main range and cuts deeply through its rocky ledges. Only a small branch of this stream heads near the summit, however, the valley proper heading a few miles west back of the San Gabriel Range, in a part of the slope that is considerably higher than the gap crossed by the railway. An outline map showing these relations is given in figure 40.

FIGURE 40.—Bird's-eye view of Cajon Pass and vicinity, California showing the general features of configuration near the Santa Fe Railway.

After passing through the deep cut west of Summit, the train follows a winding course, mainly to the west and southwest, along the side of steep slopes descending into the canyon of Cajon Creek. Along the railway grade descending from Summit there are many deep cuts through projecting spurs. These cuts reveal thick deposits of sand, gravel, and loose-textured sandstone which extend continuously northward into the Mohave Desert. These materials abut against the steep slopes of ledges of old rocks in the mountain ranges on the south, and beds apparently having a thickness of more than 2,000 feet are exposed in the descent from Cajon Summit to Cajon Creek. Cajon Creek flows east and south with sinuous course, finally running through a pass¹ between the San Bernardino Range on the east and the San Gabriel Range on the west, which affords an easy outlet into the great coastal plain or valley of southwestern California. It is 40 miles west to the next pass, and to the southeast of this gap mountains of considerable height extend for 200 miles continuously to Colorado River. Some of the most notable cuts, 60 feet deep, are near Dell siding, in one of which will be seen a remarkable framework several stories in height, designed to prevent the sand from washing and sliding into the cut.

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¹This pass has been caused by a great fault or series of parallel faults of relatively recent age geologically, crossing the axis of the general mountain range extending across southern California. These faults, one of which is the southern extension of the San Francisco earthquake rift, extend for many miles along the south foot of the San Bernardino Range and on southward into the Colorado Desert. At the pass their northwesterly course crosses the mountains diagonally, so that to the westward they define the north side of the San Gabriel Range. There were several planes of movement not far apart with huge slivers or narrow blocks of schists and other rocks between them. The latest uplift apparently was on the northeast side, for the San Bernardino Range appears to be the most recently uplifted. Its central part presents wide, relatively level areas or remnants of plains in striking contrast to the eroded top of the San Gabriel Range.

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Toward Gish the principal material is moderately compact, light-colored massive sandstone with conglomeratic streaks.¹ It contains many fragments of feldspar and quartz, evidently derived from granite.

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¹Just west of Gish, along Cajon Creek, are many prominent ledges of this rock dipping to the northeast at an angle of 20° or more. As the valley of the stream is descended (on a southeast course) the ridges on each side show numerous outcrops of the lower beds of the sandstone series about Cajon siding, and for some distance beyond. In this vicinity the beds are more and more tilted up until they dip north, or away from the mountains, at an angle of about 30°. They are believed to be of Miocene age. The railway and the valley in this locality follow the line of the faults which cut across the range.

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Halfway between mileposts 64 and 65 the canyon narrows, turns south, and passes between steep ledges of hard, older rocks of the igneous and metamorphic series constituting the mountain ranges to the east and west.²

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²Southward from this place these rocks appear extensively in the rocky slopes of the valley and they are cut by the railway grade at several points. The principal rocks are schists of greenish color. In places on the lower slopes of the valley there are remnants of narrow terrace deposits of gravel and sand, notably in cuts just beyond milepost 67, which is four-tenths of a mile beyond Keenbrook siding.

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The mountain slopes are covered with bushes in considerable variety, in great contrast to the sparse vegetation on the Mohave Desert. The difference is due to increased moisture on the ocean side of the mountains.

Near milepost 69 the canyon of Cajon Creek widens into a valley bordered by mountainous slopes, but with a wide wash in its center and a broad sloping terrace at the foot of the mountains on the north side. This terrace is terminated by a steep slope or high bank at its foot, where Cajon Creek has cut into it, a feature which is conspicuous for 2 or 3 miles. As the valley widens, however, the cut bank ends and the slope blends with the general plain, which rises gradually to the rocky ledges at the foot of the mountain. These terraces and slopes consist, of sand and gravel washed down from the mountains and deposited at their foot. On the terrace are several ranches with orchards of considerable size.

At Verdemont station the west wall of the canyon ceases as the mountain slope bears away to the west, and the railway is in the great San Bernardino plain, which is about 15 miles wide and 30 miles long, one of a series of the foothill valleys that border the southern edge of the San Gabriel Range for 90 miles. These valleys are filled with débris of unknown thickness, and their surface is made up of talus and wash from the adjacent ranges. The altitude here is 1,750 feet, and the distance to the ocean is about 50 miles. The valleys that extend to the coast lie between low ranges of granitic and other rocks. The chief of these ranges is the Santa Ana Mountains, which culminate in Santiago Peak, 5,680 feet high, and are visible on the southwestern horizon. A line of isolated hills of schist lies east of the railway for some distance beyond Verdemont, and another, which is crossed near Ono, rises into a ridge of considerable size north of milepost 78.

From Ono and beyond there is a magnificent view, to the northeast, of the San Bernardino Range (Pl. XLII), which includes many high summits. One of these, San Gorgonio Mountain, reaches an altitude of 11,485 feet, and not far west of it is San Bernardino Peak, which reaches 10,630 feet, or more than 9,000 feet above the valley land at the foot of the mountains. This high range extends far to the east but with diminished altitude and finally becomes the north side of the great desert basin in which Salton Sea is situated. At a time not far distant there were small glaciers in the higher parts of this range. From points near milepost 79 and beyond, there may be seen the remarkable scar, like a huge arrow point, on the mountain slope at Arrowhead Springs. This feature is not always conspicuous, its distinctness depending on light and foliage, but it can be discerned on close scrutiny. It is due to a peculiar-shaped area of bare rock ledges and thin vegetation. Here there is an interesting group of hot springs, some of which have temperatures exceeding 180° F. and about which buildings have been erected to form a popular health resort.

PLATE XLII.—SAN BERNARDINO MOUNTAINS, CAL. Redlands and its orange groves in the foreground. San Bernardino Peak in the center.

At Highlands Junction the main line is joined by a branch road known as the "high line," on which trains run frequently to Redlands and other points east of San Bernardino.

One other transcontinental railway, the San Pedro, Los Angeles & Salt Lake, passes though San Bernardino over the Santa Fe tracks, and another, the Southern Pacific, goes through Colton, 3 miles to the south. This city is the seat of San Bernardino County, the largest county in the United States, having an area of slightly more than 20,000 square miles, or almost equal to that of Massachusetts, Connecticut, and New Jersey combined.

San Bernardino is built over a wide area of the plain, about 5 miles south of the foot of the San Bernardino Mountains. It is an old settlement, dating back to the Spanish occupancy of southwestern California, but in the last 20 years or so it has grown into a large modern city with many industrial interests. About 15,000 acres of land in the surrounding region within 5 miles is under cultivation, mostly by irrigation. Much water is obtained from wells, many of them flowing wells, which draw their supply from the gravel and sand that constitute the plain.

The first eastern immigrants to settle in the San Bernardino Valley were a party of Mormons headed by Capt. Hunt, who came through Cajon Pass in 1851. Before this, however, there had been mission settlements in the area. One was established in 1810 near Bunker Hill, but it was destroyed by the Indians. Later a larger one was begun at old San Bernardino, on the south side of Santa Ana River. The padres in charge dug ditches, beginning between 1820 and 1830 with one from Mill Creek, which is the oldest ditch in the valley. In 1837 the mission lands were taken by the Mexican Government and given to Mexican landholders. It was from one of these landholders that the Mormons under Capt. Hunt purchased in 1851 the cultivated areas for $7,500.

At first the old ditches sufficed for the needs of the settlers, but as population increased other small ditches were dug. It was not until 1870 that the Riverside colony, made up mainly of settlers from New England, began the first large canal, but in the next 20 years many irrigation projects were developed. These utilized the greater part of the running water and considerable of the underground water. Most of the water was used for irrigating oranges and other citrus fruits. In 1904 an area of about 54,000 acres in the vicinity of San Bernardino, Redlands, and Riverside was under irrigation by water derived mainly from the San Bernardino Mountains, either from surface streams or from the underflow in the gravels at their foot.

It was soon found that the best conditions for citrus growth were to be had on the benches, where there was less liability to the low temperatures which sometimes kill the trees in the valley bottoms. The first orange trees were some seedlings grown in old San Bernardino, but it was not until the Riverside colony of 1870 was established that marketing of oranges began. The Bahia navel orange was first introduced at Riverside.¹ The principal factor in the orange business was the building of the railways which could give outlet to eastern markets; after this outlet was provided the production increased rapidly to its present great proportions. As the demand for water increased the methods of irrigation were improved, first by avoiding waste and then by careful application, so that in ordinary practice the volume used has diminished from 1 miner's inch² for 3 acres to about half as much. In the region about San Bernardino it is possible to obtain artesian water which flows under moderate pressure from the wells. The drain on this source of supply has somewhat reduced the volume and head of the water, so that the area in which flows are obtainable is now less than it was originally, though greater than it was after the dry period before 1900.

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¹The original cuttings, from Bahia, Brazil, were sent to Florida from Washington, but someone, whose identity is not now known, took two of these cuttings to California. One of these two and all the cuttings in Florida died, so that the enormous business in navel oranges has grown from the slender beginning of a single cutting. The tree that lived may still be seen at Riverside.

²A miner's inch (in California) is the amount of water which flows continuously through an orifice 1 inch square under a head of 4 inches. It equals 9 gallons a minute, 1/50 second-foot, or 1 foot deep over 14,478 acres in a year. Citrus lands require about 1 miner's inch continuous flow for every 5 acres.

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Much of the water is used in the orange groves, but fruits of deciduous-leaved trees, small fruits, and vegetables are grown, and there are many acres of alfalfa. Grapes and barley require less water and need irrigation only in dry seasons, and these and beans are generally regarded as "dry" crops. Sugar beets are a very important crop, the great refinery near San Bernardino using 40,000 tons a year.

On leaving San Bernardino the train turns from a southerly to a due west course and begins its journey through the foothill valleys along the south side of the San Gabriel Range, first running across the plain which slopes gently southward to Santa Ana River from the foot of the San Gabriel Mountains.²

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²The San Gabriel Mountains, like the San Bernardino Mountains, consist of granitic rocks of several kinds and a variety of other crystalline rocks, mainly schists, which were originally shales and sandstones, but have been altered by intrusions. It is believed that the range was uplifted in greater part in late Tertiary time. Apparently the uplift consisted of the rise of a huge block of the earth's crust along fault lines mostly trending N. 60° W. The main block was traversed by minor faults which have made the structure very complex.

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From the rear platform of the train the traveler, on leaving San Bernardino, can view the great mountain amphitheater, with its numerous ranges and peaks, which lies north of the east end of the San Bernardino Valley. Especially fine views may be had of San Gorgonio (altitude 11,485 feet), the highest peak in southern California; San Jacinto (altitude 10,805 feet), standing like a watch tower at the north end of the great range which extends southward for hundreds of miles to the end of Lower California; and San Antonio (sometimes called Mount Baldy; altitude 10,080 feet). San Antonio Peak is the highest summit of the San Gabriel Range, but not the highest mountain in southern California, as many suppose. All three of these peaks may be embraced in a single view. San Gorgonio Pass, through which runs the Southern Pacific Co.'s Sunset Route to Yuma, Ariz., and beyond, may be seen in the distance, to the southeast.

From points west of San Bernardino, Colton, 3 miles to the south, is visible. Colton has large cement works with a capacity of 3,000 barrels a day, using the marble which constitutes Slover Mountain. Peaks of granite rise at intervals to the southwest. Riverside, 10 miles to the south, is faintly visible. It is one of the greatest orange-shipping centers in the world, receiving $4,000,000 yearly for its output. Riverside is famous for its beauty, the county courthouse and the high school being examples of notable architectural achievement. Near Riverside there is a large cement plant, one of the largest in California.

Rialto, nearly 4 miles west of San Bernardino, is in the midst of a thriving irrigation district which ships over 1,200 carloads of citrus fruit annually; her crop for 1914 brought $900,000. From this village a fine view is afforded of the east end of the San Gabriel Mountains,¹ to the northwest. To the southwest, at a distance of 4 to 6 miles, is a small range known as the Jurupa Mountains, rising about 1,000 feet above the plains. They consist of quartzites, schists, and limestones, or metamorphosed sedimentary rocks, penetrated by diorite and other igneous rocks. They are in sight to and beyond Fontana. Some of the plain in this region is not under cultivation on account of lack of water.

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¹The San Gabriel Range, one of the most conspicuous and beautiful ranges of southern California, forms the watershed for the irrigation of a large part of the foothill valleys. Its individual peaks are more numerous than those of the San Bernardino plateau, and in its entirety it is a long uplifted fault block bordered on the north and south by downthrown areas.

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The village of Etiwanda is about 2-1/2 miles north of the railway station, or halfway across the plain reaching to the foot of the mountains. There are in this vicinity some large vineyards a considerable and also acreage of fruits of various kinds, notably of lemons, for which Etiwanda is famous.

Cucamonga is almost in the middle of the wide valley or plain that slopes southward from the foot of the San Gabriel Mountains to Santa Ana River. This region is extensively cultivated, in part without irrigation. It specializes in raisin and table grapes and in wines, of which it produces large quantities. The largest single vineyard in the world is located here. Cucamonga also has about 2,000 acres of oranges and lemons and 2,000 acres of peaches. From the railway fine views may be had of the San Gabriel Mountains. One peak, Cucamonga, which has an altitude of 8,911 feet, is conspicuous due north of the station, and other high ones are in view farther back in the range.

Deep canyons lead out of the mountains at short intervals, and most of these contain living streams, whose water, if not diverted by irrigation ditches, sinks immediately at the mouths of the canyons and passes as a general underflow into the gravel and sand of the slope beyond. In times of freshet the streams flow greater or less distances across the slope, carrying much sediment, which is dropped as the water spreads out on the plain. Occasional great floods cross the plains, but much of the large volume of water they carry at such times is absorbed by the porous gravels of the stream beds. The courses of these ephemeral streams are marked by dry washes, usually shallow sandy channels, many of them splitting up irregularly and some of the branches rejoining.

One effective method of conserving water in this region, where water is so valuable, is to divert the flood waters near the canyon mouth, causing them to spread out widely over the coarse deposits, into which they sink, thus adding to the volume of underflow tapped by the many wells.

At Upland station the railway passes 2 miles north of Ontario, a city on the Southern Pacific Railroad, surrounded by wide areas of orange groves and other products of irrigation. Four miles to the northwest is the mouth of San Antonio Canyon, one of the large canyons in the San Gabriel Mountains, which furnishes considerable water for irrigation. On the plain its bed spreads into half a dozen irregular washes, which are crossed by the train between Upland and Claremont. From the gravel and sand under this plain a large amount of water is pumped for irrigation. Water is saved by lining the canals with concrete and by distributing it in underground pipes, methods which prevent loss by leakage and by evaporation.

West of Claremont a spur of the San Gabriel Mountains on the north extends nearer to the railway, and the San Jose Hills,¹ a northern extension of the Santa Ana Mountains, approach from the south. Owing to these conditions the valley narrows to about 3 miles at Lordsburg. In order to pass the San Jose Hills the railway has been deflected to the northwest, a course that soon takes it near the foot of the San Gabriel Mountains, which are closely skirted from San Dimas to Pasadena. Lordsburg was originally a Dunkard settlement. It has numerous orange and lemon groves.

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¹The San Jose Hills consist mainly of a thick series of sandstones and shales of the lower part of the Fernando formation (Miocene) flexed in broad basins and arches. At their east end, south of Lordsburg, is an area of granitic rock.

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From Lordsburg to Azusa the irrigated areas are almost continuous, and many extensive and beautiful orchards may be observed at frequent intervals. Water for irrigation is brought from San Gabriel Canyon, and large amounts are pumped from wells and distributed by numerous canals.

North of San Dimas (dee'mas) a mass of sandstones and shales with interbedded volcanic rocks is exposed at the foot of the mountains. The beds dip north toward the older rocks of the range, from which they are separated by a fault.

Near milepost 112, halfway between San Dimas and Glendora, the train crosses the dry wash of San Dimas Creek, which heads in a large canyon a few miles to the northeast. It is a good example of a wash formed by a powerful intermittent stream. Beyond San Dimas Wash the train skirts the east end and north side of an isolated hill consisting of Tertiary sandstone and shale and enters the village of Glendora.

From Glendora to Azusa and in a wide area on the south are numerous orange groves and other orchards, most of them irrigated by canals from San Gabriel River, which comes out of a large canyon a few miles to the northwest. Pumping plants also add to the supply, for there is considerable water in the sand and gravel under the plain.

Near Azusa the railway is within a mile of the foot of the steep southern front of the San Gabriel Mountains, which has been followed all the way west from the mouth of Cajon Canyon and continues to Los Angeles. Two miles west of Azusa the train crosses San Gabriel Wash, the bed of San Gabriel River, the largest stream flowing from the San Gabriel Mountains. The canyon through which the San Gabriel emerges from the mountains is in sight about 3 miles northeast of the trestle over the wash. During the rainy season San Gabriel River is a stream of considerable size, furnishing water for irrigating many citrus groves and other orchards and fields on the slope south of the mountains. During the dry periods it dwindles to a mere brooklet, even within the canyon. Under ordinary conditions the wash below the canyon is dry between the canyon mouth and a point 10 or 12 miles to the southwest, where the water breaks out in springs. Some of it also comes out in Lexington Wash, near El Monte. In times of freshet a large volume of water passes down San Gabriel Wash, as may be inferred from the large bowlders in its bed. These bowlders are crushed for road material and other uses. The crusher and deep pit are on the south side of the track and a large amount of material is available in masses convenient to elevate directly into the crusher.

Monrovia station is in the southern part of Monrovia, an old settlement lying against the foot of the mountains. West of Monrovia the railway swerves to the northwest for 2 miles and then goes west through the small towns of Arcadia, Santa Anita, and Lamanda Park into Pasadena. There is a gradual ascent in this part of the line for about 350 feet.

About 3-1/2 miles south of Lamanda Park is the San Gabriel Mission, one of the 21 missions established by the Franciscans between San Diego and San Francisco. It is in an excellent state of preservation and is typical of the architecture introduced by the friars. (See Pl. XLI, B, p. 168.)

Pasadena is situated in a "rincón" or corner between the San Gabriel Range, which bears off to the northwest, and the San Rafael Hills,¹ which rise as rocky ridges nearly 1,000 feet high west of northwest of the city. It is undoubtedly these features which give Pasadena certain climatic conditions (protection from cold winds and slightly greater rainfall than that in some of the regions farther east and south) that make it particularly attractive as a winter resort. The name Pasadena is an Indian word meaning crown of the valley. Here the railway turns south to reach South Pasadena and thence goes southwest for several miles, over a low pass through the hills separating the Pasadena Plain from the Los Angeles Valley. The portion of these hills near the railway consists of soft buff sandstones and shales,² gently flexed in broad basins and arches.

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¹The San Rafael Hills are part of a low mountain block of granites and schists believed to have been unlifted between two faults trending west-northwest, parallel to a great fault here extending along the south foot of the San Gabriel Mountains. A part of the southern slope of these hills between Pasadena and Glendale is made up of heavy sandstone of Tertiary age. Eagle Rock, a well-known topographic feature here, is a picturesque outcrop of this sandstone.

²The rocks of the Monterey group are of marine origin and indicate that in Miocene time (see p. ii) the Coastal Plain region was submerged by the sea at intervals and the sands and muds were deposited in wide estuaries and along beaches. There was a long epoch of general subsidence, and a great thickness of these materials thus accumulated. They have since been uplifted, bent, and faulted, and later terraces and plains were developed across the surface.

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As the train leaves South Pasadena it enters the valley of the Arroyo Seco, which it follows to Los Angeles River, in the northern part of the city of Los Angeles. The city is built on the low river terraces, on the inner edge of the coastal plain which extends west and south to the Pacific Ocean, and on the hills of folded and faulted Tertiary sandstone and shale which rise above the plain and the terraces. Los Angeles River itself, like other streams of the arid Southwest, is a river in name only except during the heavy rains of winter, when at times it becomes a deep torrent which often does considerable damage.

Los Angeles (Spanish pronunciation loce ahn'hay-lace) is the largest city of the Southwest, in area, population, and business. It was here, in 1846, that Gen. Frémont first raised the American flag. The settlement, however, was founded in 1781, by a garrison of soldiers from the mission of San Gabriel, 65 years prior to Frémont's visit. In 1831 it had a population of 770, and as late as 1880 it was an easy-going semi-Mexican town of 12,000 inhabitants centered about the old plaza with the mission church of Nuestra Señora la Reina de los Ángeles (Our Lady Queen of the Angels), from which the city takes its name. With the coming of the Santa Fe Railway in November, 1885, homeseekers began to arrive, and a great increase in property values and the extent of the city followed. According to the United States census, Los Angeles made a greater percentage of increase in population from 1880 to 1900 than any other town in the United States, and the figures have shown remarkably rapid increase since 1900. A city census taken in June, 1915, indicates a population of 528,000. Two important factors in its growth have been the development of electric power from mountain streams as much as 240 miles away and the availability of cheap petroleum fuel.

In the northern part of the city is a belt of oil-producing territory 5-1/2 miles long, covering an area of 2 square miles. Here hundreds of derricks have been erected in close proximity to dwellings.¹

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¹The following notes are based on a concise account of the geology and technology of the California oil fields by Ralph Arnold and V. R. Garfias:

The production of petroleum in California is the most important mineral industry in the State, the annual value of the oil output equaling that of all the metals. Since 1903, with the exception of 1907 and 1908, California has annually produced more petroleum than any other State in the Union, and in 1914 the production was over 100,000,000 barrels.

The principal oil fields adjacent to Los Angeles are those of the Los Angeles district and the Puente Hills district. The Los Angeles district includes the City field, lying in the city of Los Angeles, and the Salt Lake field immediately west of the city limits, about 4-1/2 miles from its business center.

The City field was discovered in 1892, when a 155-foot shaft was sunk near a small deposit of brea on Colton Street. The first successful well was drilled later in that year on Second Street, and by the end of 1895 there were more than 300 wells. This field forms a narrow belt about 5-1/2 miles long running through the northern part of the city; the total area is about 2 square miles. The wells are from 500 to 1,200 feet in depth, and the gravity of the oil ranges from 12° to 19° Baumé. The limits of the field are well defined. The wells have always been small producers, necessitating pumping, and owing to the great number of wells drilled within a small area the field has been drained at a rapid rate and water allowed to enter the oil sands in many areas.

The first well in the Salt Lake field was drilled in 1901 by the Salt Lake Oil Co., and since 1902 this field has been the chief producer in the Los Angeles district. The wells are deeper than in the City field, ranging between 1,200 and 3,000 feet, and the average gravity of the oil is between 16° and 18° Baumé. Considerable gas under strong pressure accompanies the oil, which causes the wells to gush during the early part of their life.

The oil in the Los Angeles district is derived largely from the upper 500 feet of the Monterey group and the basal beds of the Fernando formation. During 1914 the district produced about 2,500,000 barrels of oil, and between 1894 and the end of 1914 it produced over 40,000,000 barrels. At present there are about 700 producing wells in the district. The average production in the City field is about 2-1/2 barrels a day for each well and in the Salt Lake field about 23 barrels.

The oils of the City field are uniform in quality, although they vary considerably in gravity. They contain considerable sulphur, and owing to the entire absence of light products are of little value for refining, being used almost entirely for fuel. The oils produced in the Salt Lake field show a marked similarity in general properties, being characterized by a high percentage of sulphur. The heavy oils are highly viscous, and the yield of asphalt is considerable.

The Puente Hills district, from 12 to 34 miles southeast of Los Angeles, was the second oil district discovered in California. The first producing well in it was completed in 1880. Until 1893 the Puente Hills and Santa Clara River Valley districts yielded practically all the oil produced in California. The average depth of the wells in the Puente Hills district is somewhat more than 1,300 feet and the average life of the wells about 16 years. The gravity of the oil varies between 21° and 32° Baumé.

The lighter grades of oil are believed to come from the Monterey groups, the heavier grades are derived largely from the coarser sediments of the Fernando.

On December 31, 1912, there were 470 producing wells in the Puente Hills district, and the output for the year was nearly 7,000,000 barrels. The total production of the field from 1889 to 1912, inclusive, was nearly 41,000,000 barrels. The oil produced varies greatly in composition, the greater portion being of light grade and utilized by refineries near Los Angeles.

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One notable feature in the recent development of the city has been the construction of an aqueduct 226 miles long to bring water from Owens Valley. The capacity of this line is 250,000,000 gallons a day, sufficient to supply a population of more than a million. It cost about $25,000,000. At present (July 1, 1915) the surplus water is used for the irrigation of about 8,000 acres a few miles north of the city. Los Angeles County claims to be the richest county in the United States in value of farm property and agricultural products. The estimated value of all property in the county January 1, 1915, was given at $1,500,000,000. General building operations in the city in 1913 represented an expenditure of more than $31,000,000 for materials and labor. Los Angeles has many parks, including one containing 3,000 acres, the largest municipal park in the world. There are 726 miles of improved streets, and the adjoining region has many miles of fine roads. About 25 miles south of the main body of the city is San Pedro, on the ocean, a port from which there is an extensive coast and trans-Pacific trade.

The Museum of History, Science, and Art is one of the most interesting places in the city. It has fine collections in many branches, exhibited in an attractive and instructive manner. The museum authorities control the wonderful bone deposits in the asphalt springs of Rancho La Brea, about 8 miles directly west of the city. These springs have been for centuries the most effective natural animal trap known, and the asphalt has preserved the bones of the thousands of extinct as well as modern animals caught in its deceptive and sticky pools. The skeletons of elephants, camels, sloths, saber-toothed tigers, bears, and myriads of smaller animals, including many birds, are being gradually dug out and set up in the museum. Among the bones has recently been found the skull of a human being who lived probably not less than 10,000 years ago, contemporaneously with many animals now extinct.

With the permission of the Museum of History, Science, and Art the Rancho La Brea may be visited. On the way thither the traveler passes over a portion of the great alluvial plain of Los Angeles, which is underlain, at least in part, by three Quaternary formations, the oldest of which is a marine deposit laid down horizontally on the beveled edges of a very thick series of tilted Pliocene beds. This marine Quaternary deposit has a thickness of 100 feet in the northwestern portion of the city, but thins to an edge near the ancient sea cliff beyond. Los Angeles River excavated a valley about a mile wide and 100 feet deep in the marine deposit and filled the trench with river deposits, the second Quaternary formation. This in turn is covered by the alluvium of the present plain.