Geological Survey Bulletin 845 Guidebook of the Western United States: Part F. Southern Pacific Lines

SHEET No. 28 (click in image for an enlargement in a new window)

Palm Springs Station is 7 miles northwest of Palm Springs, a popular winter resort in the valley that separates the Santa Rosa Mountains from the San Jacinto Range. The village is of considerable size and has many luxurious homes and hotels. The springs issue from the valley fill, probably rising on a fault fissure in rocks below this deposit, as the tepid water indicates a deep-seated source. The water has a very low mineral content (243 parts per million), mostly sulphates and chlorides of sodium and potassium, silica, and a small amount of sulphureted hydrogen, which soon passes off. The flow, estimated by Brown at about 10 gallons a minute, makes a pool some 60 feet in diameter.

These springs belong to "Mission" Indians, who live on several small reservations in the valley. These people are of the Yuman family, now greatly diminished in number. At a place about 1 mile north of Coachella siding the United States Government has a small pumping plant to supply well water for irrigation on the Cabazon Indian Reservation.

The San Jacinto Mountains present steep slopes, especially to the northeast, Snow Creek, for example, dropping 4,000 feet in 1 mile of its course, and many other deep canyons head in this slope. The southwest side of this range is less steep and is bounded by the San Jacinto fault, movement on which in 1899 and 1918 caused serious earthquakes in San Jacinto and Hemet. The east side of the range is also very precipitous, for at Palm Springs, which is at an elevation of 455 feet, steep slopes rise more than 10,000 feet to the summit, San Jacinto Peak, as shown in Plate 42, A. This steep front is largely due to a great fault trending north, which is clearly exposed just west of Palm Springs Station. Here the mountain face consists of granite and gray marble in layers that dip 75° or more to the northeast, and a prospector's tunnel shows a fault breccia with slickensides. This fault probably passes under the settlement at Palm Springs, for it is well exposed a few miles south of that place, where the planes of movement are marked by wide bands of crushed and strongly weathered rock. There are springs along this broken zone, and also tufa deposits 20 feet thick covering several acres, marking the position of ancient springs. Apparently this fault is now quiescent. There are several branch and cross faults in the Murray Hill district, on the east side of the valley about 5 miles southeast of Palm Springs. (Frazer.)

Above Palm Springs Station the Coachella Valley becomes narrower as it rises into San Gorgonio Pass, which separates the San Jacinto Mountains on the south from the San Bernardino Mountains on the north. The principal narrowing takes place near the mouth of Whitewater Canyon, on the west side of a north-south fault on which a block of the old hard rocks is uplifted. Above this fault the side slopes become steeper, notably on the south side of the valley, where they rise 9,500 feet to San Jacinto Peak. On the north side there is a rise of about 6,000 feet to the crest of a high outlying ridge on the south slope of the San Bernardino Mountains. This gives a steep-sided profile, but the valley bottom appears nearly flat in cross section, and its center is occupied by wide, boulder-filled washes containing material moved by the occasional freshets.

The streams flowing out of the mountains are building alluvial fans of large size, one of the most conspicuous of which is at the mouth of Snow Creek Canyon, south of Fingal siding, not far beyond Palm Springs Station.

San Gorgonio Pass is a dropped block of the earth's surface carrying an extensive body of recent sediments and lying between two great ranges of crystalline rocks. It is from 2 to 3 miles wide, and it extends almost due east and west for about 18 miles in the ordinary application of the name. To the east it merges into the Coachella Valley and to the west near Beaumont into the wide Beaumont Plain. Many of its relations have been discussed in detail by Russell, who regards the south wall as a fault scarp which has been moderately active in recent time, but the northern side is probably an old denuded thrust block face. The sediments at the margin of the pass were deposited under conditions somewhat similar to those now prevailing.

In 1800 to 1850 many American explorers, mostly hunters, came into the lower Colorado River region. It is stated that in the gold rush of 1849-50, 10,000 people crossed the Colorado River at Yuma. The earliest trail ran from Yuma, passing south of the southeast end of the sand hills through Mexico, thence along the Alamo River, across the present Imperial Valley, up the valleys of Carrizo and San Felipe Creeks, and over Warners Pass behind the Santa Rosa and San Jacinto Mountains to the coast. It was along this route in 1848 that Lieut. W. H. Emory led a military reconnaissance, and in 1857 it was used by the stage line to San Diego and by the Butterfield stage line the following year. San Gorgonio Pass was discovered in 1774 by Padre Francisco Garcés, who went through it on the way to Mission San Gabriel and named it Puerto de San Carlos. It was traversed again in 1775 by Juan Bautista de Anza on his expedition to found San Francisco. The first American exploration was made in 1853 by a party under Lieut. J. G. Parke, of the United States Engineers, with W. P. Blake as geologist, members of the expedition sent out to discover a route for a transcontinental railroad through the great mountain barrier of California. The party was delighted to find the fine, low natural gateway of San Gorgonio Pass, which they considered the best pass in the Coast Range. In it was the ranch of a Mr. Weaver, who had settled there several years before. The narrative of this discovery is an interesting record. The expedition descended the Coachella Valley to the Salton Basin, which was ascertained to be several hundred feet below sea level. The scarcity of water, however, made this route too difficult for caravans, and the old route by way of San Felipe Creek and over the high divide as described above was preferred until after the railroad was built through in 1879;⁸⁵ then wells were sunk and water found in the deposits underlying the valleys. Now there is ample supply at short intervals, especially along the main highway, which passes up the valley to San Gorgonio Pass but goes by way of El Centro and along the southwest side of Salton Sea. Water at Palm Springs, Toro Spring, Agua Dulce, and Indian Wells has long been utilized by the resident Indians, as well as by their predecessors the Cajuenches, a tribe of Yuman stock who were found by Garcés occupying the Colorado Desert region as far west as San Gorgonio Pass.

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⁸⁵In 1876 a stage line crossing the Colorado River at Ehrenberg, 60 miles above Yuma, came by way of Dos Palmas Spring, east of Mecca, and thence up the Coachella Valley to San Gorgonio Pass.

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With increase in elevation the vegetation of the valley floor as well as that of the mountain slopes changes rapidly, and the desert flora ceases near the 1,500-foot contour. This, however, is largely due to the fact that considerable moist air comes through San Gorgonio Pass at times, and on the mountains there is much more precipitation than in the desert ranges to the east. The Spanish bayonet (Yucca mohavensis) is conspicuous near Cabazon siding and for some distance west. (See pl. 42, A.)

From the vicinity of Cabazon (misspelling of Spanish cabezón, big head) westward there are very impressive views of the mountains, especially of the San Bernardino Mountains, to the north. As shown in Figure 64, there are wide, flat-topped foothills on the north side of the valley.

FIGURE 64.—Cross section of San Gorgonio Pass near Cabazon siding, Calif., looking east. gr, granite; ss, sandstone; sc, schist; Qal, alluvium.

Banning, near the head of the valley constituting San Gorgonio Pass, is an agricultural and residential settlement where high elevation and other conditions make it an agreeable summer resort as well as an all-year residence. The mean annual temperature is about 60°, the average humidity ranges from 42 to 53 per cent, and the mean annual precipitation is 18.5 inches. It is claimed that there is an average of 345 days of sunshine in the year. The views of the mountains to the north and south are very impressive, and roads lead from Banning into both ranges. The great crest of San Gorgonio Mountain (elevation 11,485 feet), a few miles north of the pass, is most conspicuous, and often its summit remains snow-covered long after the fruit trees of the lowlands are in blossom. This is the highest point in southern California. San Jacinto Peak is also a prominent feature not far to the southeast.

The water used for irrigation at Banning is taken from the San Gorgonio River, which has an average flow of about 16 second-feet. There are many orchards of peaches, prunes, almonds, and other fruits near Banning, and through Pershing siding to Beaumont and beyond, almond trees blossoming in early February are an attractive sight. The 28-mile tunnel to carry water from the Colorado River at Parker to Los Angeles will pass near Beaumont, where it will be about 800 feet below the surface. This water is to be impounded by the Boulder Dam.

The San Bernardino Mountains (see fig. 65) consist of a great mass of schists of various kinds, greatly contorted and invaded by granites, some of which have also become schistose owing to movement and great compression. There are excellent exposures of these rocks in the canyons of Smith Creek and the San Gorgonio River northeast of Beaumont. On the south side of the San Bernardino Mountains the schist laminae dip 30° NE., and the peak called San Bernardino Mountain (10,630 feet above sea level) consists of biotite schist. The rocks around San Gorgonio Mountain range from biotite granite to schist, both intruded by granite. From the Whitewater River to Deep Canyon the schists dip mostly 20° N., with many local variations. The great offset in the mountain front at the Whitewater River referred to above is due to faulting. (Vaughan.)

FIGURE 65.—Section from Banning, Calif., north to San Bernardino Mountain. After Vaughan.

Snow is conspicuous in winter on the higher ranges in southern California, but it disappears in summer. Formerly there were small local glaciers on the San Bernardino Mountains, as shown by well preserved cirques and moraines.⁸⁶ The moraines do not extend far beyond the cirques, and there are no typical glaciated valleys. The detritus is angular, and the boulders are not striated. A typical cirque on the northeast side of San Gorgonio Mountain is about 1,500 feet long, 1,000 feet wide, and 1,200 feet deep. It contains a terminal moraine 250 feet high and two small recessional moraines that mark stages in the shrinking of the glacier. Doubtless the last glacial ice disappeared many centuries ago. Other features of former glaciation occur at the head of Hathaway Creek, just north of San Bernardino Mountain, where there was a tongue of ice about a mile long. None of these glaciers extended below an elevation of 8,500 feet, and they were all on the northward-facing slopes.⁸⁷

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⁸⁶Cirques are steep-walled semi-circular recesses in the high mountain slopes, produced by glacial erosion, and moraines are ridges of coarse ice-borne detritus that accumulates along the margin of glaciers as the ice melts.

⁸⁷Fairbanks, H. W., and Carey, E. P., Science, new ser., vol. 31, pp. 32-33, 1910. Vaughan, F. E., California Univ. Dept. Geology Bull., vol. 13, p. 335, 1922.

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North of Banning is the Morongo Indian Reservation. Padre Font, who was the chronicler of Anza's expedition in 1774, described some Indians living hereabouts whom they named Danzarines (Spanish danzrín, a fine dancer), because of their habit of gesticulating constantly while talking.

A short distance east of Beaumont the railroad passes through the wide saddle between the San Jacinto and San Bernardino Ranges at an elevation very near 2,600 feet, leaving the drainage basin of the Gulf of California and entering a region where the streams flow directly into the Pacific Ocean, which at its nearest point lies 55 miles almost due southwest of Beaumont.

Beaumont is an agricultural settlement and year-round resort. From Beaumont west there is a down grade past Nicklin and Hinda sidings into the San Timoteo Canyon, which leads to the Santa Ana River. In the upper part of this canyon there are at intervals fine views of the mountains to the north, but finally high banks cut off the view. San Timoteo Canyon is excavated in a deposit of loam, sand, gravel, and cobblestones of Pleistocene age. These materials are well exposed in gullies and banks in the adjoining hill slopes. Together with underlying deposits of Pliocene age they constitute the wide ridge of badlands on the south separating San Timoteo Canyon and San Jacinto Valley. The materials here are mostly coarse sand and cobble beds in a matrix of sand, underlain by soft sandstones and shales of gray-brown, yellow, and reddish tints. The structure of the ridge is strongly anticlinal, the beds on the north side and center dipping northeast and those on the south side dipping southwest into the Moreno-San Jacinto Valley. The axis of the anticline is some distance south of the crest of the ridge. It is covered by valley fill in slopes 20 miles west of Beaumont, but its extension to the northwest is shown in Bunker Hill and other outcrops to the northeast. Some features of the steeply dipping beds are shown in Plate 43. There are fine exposures of them on the highway that crosses the ridge 3 miles west of Beaumont. The strata forming this ridge, especially the lower members, contain many bones of extinct animals, comprising camels, a large and a medium-sized horse, ground sloth, tortoise, peccary, antelope, saber-tooth tiger, mastodon, rabbit, bear, and others—an assemblage of late Pliocene and early Pleistocene time, creatures mostly very different from the present fauna. (Frick.)

PLATE 43.—A (top), VIEW EAST UP SAN TIMOTEO CANYON AND ACROSS YUCAIPE BASIN FROM A POINT 1 MILE SOUTH OF REDLANDS, CALIF. Tilted late Tertiary strata at right; San Bernardino Mountains at left. (Mendenhall.)

It is believed that in late Pliocene time southern California had somewhat the same configuration as at present. The land was gradually rising, and on the narrow coastal margin was deposited a thick succession of marine beds. Much of the material was sand and clay of local origin. The animals were an assemblage of forms that would now look strange in this region. In the open meadows were droves of slender-limbed horses, various kinds of camels, including two of giant size, and many antelope and deer. In the brush were pigs, the large boar, and tapirs, and in the forest were saber-toothed tigers, ground sloths, wolves, and bears larger than the great Kodiak bear of Alaska. From the time of deposition of the lower sediments to that of the upper ones, there was considerable change in the fauna and the horses especially became larger and of a more advanced type. It is estimated that this was considerably more than a million years ago. (Frick.)

The Tertiary and overlying formations lying on the granite south of Beaumont and extending westward nearly to Riverside have a total thickness of more than 4,000 feet. At the base is about 1,800 feet of red conglomerate and sandstone, unconformably overlain by about 1,500 feet of sandstone and shale, all of late Tertiary age. The lower beds are well exposed along Potrero Creek and its tributaries, south of Beaumont. (Frick.)

The uplift and flexing of the strata in the ridge south of San Timoteo Canyon were geologically recent, probably contemporaneous with the early part of the uplift of the San Bernardino Mountains. It is probable that at the same time the San Bernardino Valley subsided somewhat, so that its rock floor, sheeted over by silt and sand, stood at a lower level than at present. Streams cut deep canyons in the mountains and carried boulders, rocks, and clay out over the plain until many hundreds of feet of alluvial material was accumulated. (Mendenhall.)

On approaching El Casco siding there is in view a steep-sided gully cut in the relatively level valley floor of fill, showing that there have been two stages of valley development—an earlier one, followed by some deposition, and the present one of invasion by a stream cutting rapidly to a lower grade.

A few miles farther down grade San Timoteo Canyon opens into the eastern part of the San Bernardino Valley, which is traversed by the Santa Ana River, a large stream draining an area of considerable extent in the San Bernardino Mountains and used extensively for irrigation. Probably no other stream of its size in the United States is made to serve more varied uses. In its course of not more than 100 miles from the headwaters to the ocean the same water is used at least seven times for power and irrigation, by means of artificial storage, diversion into canals, and recovery of seepage water by pumping.⁸⁸

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⁸⁸See U. S. Geol. Survey Water-Supply Paper 636, pp. 176-177, 1930.

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The railroad passes through Redlands station 3 miles south of the fine city of Redlands, which is noted for its oranges (see pl. 42, B) and for the beauty of its environment. A park including Smiley Heights, with a notable collection of fine trees, offers some spectacular drives with charming views of orchards and vistas of the great stately San Bernardino Mountains, their higher peaks capped by snow for a large part of the year. (See pl. 44, A.) Six miles northeast of Redlands is the deep canyon of the Santa Ana River, which is followed by a road that gives access to some of the many resorts in the higher parts of the San Bernardino Mountains. Near by are the Urbita Hot Springs, with a large swimming pool and sulphur and mud baths. The Redlands district is at the eastern margin of the great orange belt of southern California. The soil is favorable, being a porous sandy loam that keeps free from alkali under irrigation, and much of the land is sufficiently high to be safe from frost, which occasionally occurs in the lower part of the valleys on chilly mornings. Water for irrigation is both pumped from the large underflow from the Santa Ana Wash and diverted from the Santa Ana River and Mill Creek.

PLATE 44.—A (top), SAN BERNARDINO PEAK FROM POINT NEAR REDLANDS, CALIF. The snow-capped mountain overlooks orange trees in fruit. B (bottom), MAGNOLIA AVENUE, RIVERSIDE, CALIF. This avenue, with its border of palms and pepper trees, is one of the world's most beautiful thoroughfares..

The Santa Ana River is crossed about 7 miles west of Redlands and the city of Colton is entered. Colton is an important commercial and railroad center. Among many other industries it has a large plant for icing refrigerator freight cars that carry fruits and other perishable products on the long trip across the warm Imperial Valley and the deserts of southern Arizona and New Mexico. In this region the mean annual precipitation is about 14 inches, varying usually from 10 to 18 inches. The humidity is generally only 30 to 40 per cent, so that the summer heat is seldom uncomfortable.

Colton has a cement works with a capacity of 3,000 barrels a day, using the marble that constitutes Slover Mountain, just west of the city, and there is another large plant near Riverside. Southwest of the city many small peaks of granite rise above the plain.

Riverside (population 29,696, an increase of more than 50 per cent from 1920 to 1930), visible 7 miles south of Colton, is one of the greatest orange-shipping centers in the world, receiving nearly $4,000,000 yearly for its output. (See pl. 45.) The city is famous for its general beauty, the original navel orange tree, the Mission Hotel, and Magnolia Avenue, with its 10 miles of quadruple rows of eucalyptus, pepper, palms, and magnolias. A portion of this avenue is shown in Plate 44, B. The parent of millions of orange trees (which in 1874 came to Riverside as a seedling sent by the Department of Agriculture) now stands protected by a high railing, in a position of honor in front of Mission Inn, where President Theodore Roosevelt replanted it in 1903. The county courthouse and the high school at Riverside are notable examples of architectural achievement. There is also a large Indian school. On Mount Rubidoux is a cross dedicated to the memory of Padre Junípero Serra. This knoll takes its name from a trapper who owned the Jurupa ranch, the site of Riverside, which at first was named Jurupa.

PLATE 45.—A (top), PICKING LEMONS NEAER RIVERSIDE, CALIF.. B (bottom), ORANGE GROVES NEAR RIVERSIDE.

The name San Bernardino Valley was given by Garcés in 1774 to the plains adjacent to the upper portion of the Santa Ana River, but it is now applied to the continuation of these plains that extend for 90 miles along the south side of the east end of the San Gabriel Mountains to and beyond Pomona, an area of about 1,500 square miles. This valley is filled with débris of unknown thickness, and its surface is made up of deposits of sand, silt, and gravel, the talus and wash from the adjacent ranges. The elevation along its north side is about 2,000 feet, and the distance from its southern margin to the ocean is about 50 miles. To the south and west are low ranges, the chief of which is the Santa Ana Mountains, culminating in Santiago Peak, 5,680 feet high, visible on the southwestern horizon.

To the northeast are many high peaks of the San Bernardino Mountains, which were skirted by the railroad from Whitewater to Beaumont. These peaks are often visible from ships at sea.

On the south slope of these mountains, near Arrowhead Springs, there is a remarkable scar, like a huge arrow point. (See pl. 46, A.) It is not always conspicuous, its distinctness depending on light and foliage, but it can be easily discerned on close scrutiny. It is due to a peculiar-shaped area of bare rock ledges and thin vegetation, 1,375 feet long and 449 feet wide, occupying an area of 7-1/2 acres. Near by is an interesting group of hot springs, some of which have temperatures exceeding 180° F.; here buildings have been erected to form a health resort. The water rises on the fault that defines the south margin of the range, and the heat is due to the great depth from which it comes.

PLATE 46.—A (top), THE GREAT ARROW-SHAPED SCAR IN THE MOUNTAIN SIDE AT ARROWHEAD SPRINGS, ON SOUTH SLOPE OF SAN BERNARDINO MOUNTAINS, CALIF. B (bottom), UPTURNED LATE TERTIARY STRATA IN CAJON PASS, NORTHWEST OF SAN BERNARDINO, CALIF.

Three miles north of Colton is the prosperous city of San Bernardino (population 37,481), the county seat of San Bernardino County. This is 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 on the plain, about 5 miles south of the foot of the San Bernardino Mountains, and in the last 30 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 is under cultivation, mostly irrigated by water from wells, many of them flowing, which draw their supply from the gravel and sand that constitute the plain. San Bernardino was the first Anglo-Saxon settlement in southern California, established in 1851 by a colony of Mormons sent from Utah by Brigham Young. They came through Cajon Pass (cah-hone') and purchased from Mexicans the cultivated areas of the Bernardino ranch for $7,500. The region had long been occupied by settlers of Spanish origin. In 1810 a mission was established 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 the Santa Ana River. There 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 settlers, and it was from one of these landholders that the Mormons purchased land for their settlement.

At first the old ditches sufficed for the needs of the settlers, but as population increased other ditches were dug. In 1870 the Riverside colony, made up mainly of settlers from New England, began the first large canal, and in the next 20 years irrigation was extended over a wide area. The greater part of the running water and considerable underground water was utilized, mainly for irrigating oranges and other citrus fruits. Now a large area in the vicinity of San Bernardino, Redlands, and Riverside is under irrigation by water derived either from surface streams from the San Bernardino Mountains or from the underflow in the gravel at their foot.

It was soon found that the best conditions for citrus growth were on the benches, where there was less liability to the low temperatures that sometimes kill the trees in the valley bottoms. The first orange trees were 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. The original cuttings, from Bahia, Brazil, were sent to Florida from Washington, but someone, whose identity is unknown, took two of these cuttings to California. One of these two and all the cuttings in Florida died, so that the present 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.

The principal factor in the orange business was an outlet to eastern markets, and after the building of the railroads production increased rapidly and finally attained the 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 was diminished from 1 miner's inch for 3 acres to about half as much.⁸⁹ In part of the region about San Bernardino artesian water is available. It flows under moderate pressure from the wells, but the heavy drain on this resource has reduced the volume and head of the water, so that the area in which flows are obtainable has greatly diminished. It was decreased temporarily by the dry period before 1900.

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⁸⁹A miner's inch (in California) is the amount of water that flows continuously through an orifice 1 inch square under a head of 6 inches. It equals 11-1/4 gallons a minute, 1/40 second-foot, or 1 foot deep over 18.1 acres in a year. (The older miner's inch was 1/50 second foot.) Citrus lands require about 1 miner's inch for every 5 acres.

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Much of the water is used in orange groves, but large tracts of other fruits, vegetables, and alfalfa are irrigated. Grapes, beans, and barley, which require less water and need irrigation only in dry seasons, are regarded as "dry" crops. Sugar beets are a very abundant crop, the refinery near San Bernardino using 40,000 tons a year. Oranges are available for a long period, the navels in winter and the Valencias in spring and summer. Lemons ripen practically throughout the year. In San Bernardino County vineyards cover 40,000 acres and give employment to many persons. (Turn to sheet 29.)