Geological Survey Bulletin 614 Guidebook of the Western United States: Part D. The Shasta Route and Coast Line

SHEET No. 2A (click on image for an enlargement in a new window)

The prominent sharp ridge on the right, north of Somis (see sheet 2A, p. 110) in which light-colored and reddish formations are exposed, is the west end of Oak Ridge. It is composed largely of Monterey shale, which in places has been turned brick-red though the oxidation of its former oil content. The hills between Somis and Oak Ridge consist largely of the Fernando formation.

In Pleasant Valley in the neighborhood of Somis and Camarillo (ca-ma-reel'yo) there are 17,800 acres of beans now growing. Large quantities of honey, walnuts, and dried fruit are also produced here. On the left (east) a few miles from Camarillo is the bold northwest end of the Santa Monica Range. At its base can be seen a quarry of a gray igneous rock that is extensively used by the railroad for ballast. The terrace near Moorpark has a counterpart in the vicinity of Camarillo, due partly to stream action and partly to wave action.

The hills north of Pleasant Valley have been carved by erosion from a broad east-west anticline which lies south of the main Oak Ridge arch. The west end of this anticline disappears (plunges) under the alluvium of the Hueneme (way'nay-may) Plain. Its flanks are covered by the soft Fernando beds, which extend northward across Santa Clara Valley.

Under the Hueneme Plain is one of the best-developed artesian basins in southern California. The wells range in depth from about 50 to 200 feet and yield a good flow of excellent water that is utilized for irrigating beans and sugar beets, which are produced in enormous quantities.

Oxnard is surrounded for miles by fields of beans and beets and is one of the greatest sugar and bean centers in the world. In the large factory seen to the left of the railroad as the train enters the town 3,000 tons of beets are sliced daily and l,500 carloads of sugar are produced annually.

A sinking of the land less than 100 feet, a moderate depression in comparison with movements that are known from geologic evidence to have taken place along the California coast, would cover the whole Hueneme Plain with salt water. The plain is doubtless the old delta of Santa Clara River, which is crossed at milepost 404, near Montalvo.

From Montalvo a branch of the Southern Pacific runs up Santa Clara River to the oil district and connects with the San Joaquin Valley line of the same company. Immediately northeast of Montalvo are the remnants of one of the old sea or river terraces, and half a mile farther northwest is another remnant. The hills north of Santa Clara River, between Montalvo and Ventura, consist of Fernando beds, from 8,000 to 10,000 feet in total thickness. Fossils found in different layers indicate that this formation ranges in age from the upper Miocene to Pleistocene. (See table on p. 94.) The beds are soft and form the south side or limb of a broad anticline whose axis crosses Ventura River in an east-west direction about 2-1/2 miles north of the city of Ventura. Consequently the beds near Ventura dip south, whereas those north of the anticlinal axis dip north. Knowledge of such structural relations as are here outlined is very important in prospecting for oil. This great area of Fernando beds extends northeastward for about 20 miles as a belt of relatively low hills between Sulphur Mountain on the north and Santa Clara River on the south.

Sulphur Mountain is an anticlinal fold of Monterey shale. The fold is overturned toward the south, and the steepness of the south face of the mountain is due to this structure. This steep face is plainly visible in clear weather from the railroad between Santa Paula and Montalvo. Some of the best oil in the State comes from wells on the south face of Sulphur Mountain.

The city of Ventura (abridged from San Buenaventura) is pleasantly situated on the terraced slopes overlooking the sea between the mouths of Santa Clara and Ventura rivers. Besides being a delightful seaside resort it manufactures some machinery and has a large trade in beans, sugar beets, apricots, and other crops. With its many charming homes, wealth of flowers, and lawns of the Japanese clover (Lippia repens), Ventura invites more than the passing glimpse to be had from the train. Its mission, built in 1782, is still in use and may be seen, together with the county courthouse, from the train by looking up the streets on the right, soon after leaving the station.

A branch line runs from Ventura up Ventura River to Nordhoff, 16 miles away, in Ojai (o-high') Valley, inclosed by mountains of which Topatopa (6,351 feet) is chief. The wild Matilija (ma-tee-lee'ha) Canyon and Wheelers Hot Springs are near by. Nordhoff is noted as a winter resort. The route from Ventura thither crosses the Fernando, Monterey, and Sespe formations and the Sulphur Mountain fault.

On the west side of the mouth of Ventura River, about a mile north west of Ventura, are some finely developed sea terraces. The train skirts one of these on the right, and the deep gullies expose the sand and gravel on its outer edge. Remnants of the same terraces, some of them extending up to an elevation of about 500 feet, may be noted at several points from Ventura northwestward for 15 or 20 miles to the vicinity of the mouth of Rincon (rin-cone') Creek. That these terraces mark the positions of old sea beaches is known to the geologist not only from their form but from other more convincing evidence. Along the beaches of the present day live clamlike mollusks (Pholas) which by turning round and round and using their shells as a sort of auger, bore for themselves holes in the rock in which they live. Holes unmistakably formed in this way can be found along the inner edges of some of the terraces that are now hundreds of feet above the ocean. Moreover, the gravels that lie on the terraces contain many species of marine shells.

For 2 or 3 miles west of Ventura the road lies on a low terrace about 40 feet above the waves. Just beyond milepost 394, on the right, is a prominent hill that was formed suddenly about 40 years ago by a landslide that buried the stage road.

The hills along this part of the coast consist of coarse conglomerates and sandstones of the Fernando formation, dipping westward at an angle of about 45°. Toward the northwest the shore line cuts lower and lower into the formation, exposing soft sandstones and sandy shales.

Beyond Los Sauces Creek (sow'ses, Spanish for the willows), having crossed the anticline referred to on page 104, the traveler comes at milepost 388 to bold bluffs of the Fernando beds, which dip to the northeast and are overlain by the horizontal Pleistocene beds of an uplifted marine terrace. A generalized cross section from the shore to Rincon Mountain (fig. 14) illustrates the apparent relations of the formations in this region.

FIGURE 14.—Generalized cross section from the Pacific Ocean to Rincon Mountain, Cal., showing apparent relations of the formations.

At a point 12 miles northwest of the mouth of Ventura River, near milepost 385, between Seacliff and Rincon Point (Benham), the shore line crosses the contact between the Fernando and the Monterey formations. Remnants of terraces are to be seen all along here at different heights above sea level. The layers of the Monterey shale, as a rule, are highly contorted and wide areas of intricately crumpled shale are laid bare at low tide. In general the beds dip to the south at fairly high angles. The canyons which cut into the shale are sharp and steep sided and afford excellent exposures of the rocks.

At several places dark-colored oil sands are interbedded with the shale. The saturation of these sands is so small and the structure is so unfavorable that no productive wells have yet been drilled between Punta Gorda and Carpinteria.

At Benham the railroad crosses Rincon Creek, which is here on Monterey shale, and traverses an alluvial plain for several miles. An asphalt mine is plainly visible on the left side of the track. Large quantities of this black asphalt soaked sand have been mined out of the sea cliff and the asphalt distilled from it in the old refinery near by. The underlying shale (Monterey), from which the oil oozed into the Pleistocene deposits and there evaporated in part to form the asphalt beds, is visible in the bottoms of the pits, and is also well exposed in several cuts along the track immediately south of the refinery. One deep well has been drilled in the Monterey beds half a mile east of the refinery, but no commercial deposits of oil were found.

Carpinteria (car-pin-tay-ree'ah, Spanish for carpenter shop) was named in August, 1769, by Friar Juan Crespe and his companion pioneers, who found the Indians making dugouts. Here is a wonderful grapevine, probably as old as the missions, whose trunk is 8 feet in circumference, larger than any other known on the continent. Its enormous yield of 15,000 to 20,000 pounds of grapes is unequaled, being several times more than the yield of the famous vine at Hampton Court, England.

On a sea terrace nearly 2 miles wide along the hills back of Carpinteria great quantities of fruit, nuts, and beans are raised. Beyond this alluvial terrace rises a sharp ridge composed of the Topatopa and Sespe formations, dipping at angles from 60° to 75° toward the coast. These beds are cut by a pronounced fault on the north side of the ridge. Still farther north, visible from the train, is the main Santa Barbara Range, which consists of a great anticline overturned to the south and exposing the beds of the Topatopa formation and the overlying Sespe. The beds on the south side of the range dip northward in consequence of this overturn. West of Carpinteria the terrace gradually narrows. A lagoon visible on the left indicates slight recent subsidence of the coast.

The high ridge of Topatopa and Sespe rocks extends to Toro Canyon, northeast of Summerland. From this point it slopes off into the hills north of Summerland, which are composed of red sandstones and shales (Sespe), black shales and some interbedded sands (Vaqueros), and the overlying diatomaceous shales with two interbedded layers of volcanic ash of the Monterey group, all dipping toward the coast at high angles.

The people of Summerland, once a pleasure resort, are now successfully invading the adjacent ocean bed and pumping oil out of it (Pl. XXVI, p. 108). The sight of oil derricks on piers extending out into the ocean is unique. The wells range in depth from 300 feet near shore to 1,200 feet at the end of the longest wharf.¹

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¹ The Summerland oil field was opened in 1891 and was soon completely drilled. Only a few of the wells are now being operated, and these produce an average of about 2 barrels a day apiece. On Dec. 31, 1912, the Summerland district contained 152 producing wells, and the production for that year was 65,376 barrels. In 1894 the production was 1,500 barrels. The greatest annual production was 208,370 barrels, the quantity produced in 1899, and the total production from 1894 to 1913, inclusive, was 1,867,594 barrels. The oil is dark brown or black and ranges in gravity from 9° to 18° Baumé. It is used principally for the manufacture of asphalt, for fuel, or for road dressing.

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PLATE XXVI.—SUMMERLAND OIL FIELD, CAL.

At Summerland the Monterey group is overlain by the Fernando formation, both dipping toward the sea. A local anticline is developed in these Fernando beds, and on the flanks of this arch and in the area underlain by the seaward-dipping beds is located the Summerland oil field. The Fernando beds are overlain by coarse, nearly horizontal beds of Pleistocene age which underlie the soil over the whole Summerland-Carpinteria terrace. These beds are impregnated with oil in the sea cliff in Summerland, and the productive beds of the Fernando are also oil-bearing where exposed along the same cliff. A conspicuous unconformity between the two formations is exposed near the north end of town.

Miramar (Spanish for behold the sea), a village remarkable for its wealth of flowers, is between Summerland and Santa Barbara. The land here slopes gradually up from the ocean toward the foot of the range. This even slope is the surface of an alluvial deposit brought down by streams from the mountains. Such deposits at the mouths of canyons are known as alluvial fans or alluvial cones.

The low hills seen to the right (northwest) on the way between Miramar and Santa Barbara are the remains of one or more old sea terraces that flank the range in the vicinity of Santa Barbara and have been partly eroded away. The south face of these hills consists of Monterey shale, dipping steeply toward the north and behind them toward the mountains, are successively the Vaqueros and Sespe formations. The principal part of the range, as previously described, consists of steeply dipping beds of the Topatopa formation.

A local anticline extending in a southeasterly direction is developed in the hill about three-fourths of a mile west of Montecito. This affects the Fernando formation much like the anticline at Summerland, but although the Summerland fold yields oil the Montecito fold does not.

Near Santa Barbara the train passes a lagoon which, like that at Carpinteria, indicates a recent settling of the coast.

The city of Santa Barbara lies in a broad valley between the Santa Ynez (ee'ness) Range on the northeast and a group of low hills on the southwest. To the southeast this valley opens on the Santa Barbara Channel. The inclosing hills rise in gently sloping sea terraces on which in great part the city has been built. Sheltered from the ocean winds by the hills to the west and looking out over the sparkling blue waters of the channel, Santa Barbara enjoys a situation and a climate that have made it famous as a resort and give its gardens such beauty as can be found in few other places in the world.

The old mission church, built in 1786, is one of the best preserved in California and has been pictured on hundreds of post cards and photographs. It is well worth visiting.

Lavigia Hill, directly southwest of the city, is composed chiefly of beds belonging to the Fernando formation, containing at a number of places well-preserved fossil sea shells of Pliocene age. At the east base of the hill, near the bathhouse, is an exposure of soft limy beds (marl) containing fossil marine shells and impressions of the moss-like sea animals known as bryozoans. These also are Pliocene. Along the coast west of Santa Barbara Point the Monterey shale is exposed underlying the Fernando beds of Lavigia Hill.

The hills lying at the foot of the main range just north of Santa Barbara and extending westward for several miles have been shaped by erosion from one or more old marine terraces which formerly stretched along the seaward base of the range.

The railroad, from a place near Santa Barbara to Point Conception, a distance of about 40 miles, follows a well-defined shore terrace but little above sea level. On and near this terrace are walnut groves, orchards, bean plantations, and broad areas of rolling oat and barley hay lands. From it may be had broad outlooks over the sea, with its floating masses of sea weed, now mapped by the Government as a possible source of potash, and inland views of the rugged Santa Ynez Range, with its white rocks projecting from what at a distance looks like a mossy cover of chaparral. This terrace is capped by soft conglomerates and sandstones which show in many railroad cuts their horizontal beds, wonderfully sculptured into vertical forms by the heavy rains of winter. (See Pl. XXVII.) These uplifted shore deposits, representing the combined action of sea waves and land streams, are well exposed about 6 miles north of Santa Barbara (at 365-miles from San Francisco), where they rest on upturned and contorted beds of Monterey shale.

PLATE XXVII.—SCULPTURED CLIFFS ALONG COAST LINE NEAR SANTA BARABARA, CAL. The cliffs consist of gravel, sand, and clay that cap the prominent marine terrace by the railroad.

At Goleta (go-lay'ta, Spanish for schooner), amid walnut groves on the right, is a nursery of the Southern Pacific Co., in which are grown trees, shrubs, and flowers to ornament the station grounds and to plant on drifting sands in order to prevent their covering the railroad. An example of this treatment of sand will be seen beyond Point Arguello (ar-gwail'yo, Spanish for faintness), where the Santa Ynez Mountains end at the ocean. A large lagoon on the left, just west of Goleta, indicates coastal sinking.

On the right, north of Elwood, is a famous olive grove and oil factory. West of Elwood some of the larger streams from the mountains have gashed the terrace which the railroad is following, and some beautiful views of ravines and sea may be enjoyed from the car window. This is practically true from Bell Canyon (milepost 358) west to Gaviota. The larger canyons cut back into the mountains, exposing the several southward-dipping formations in series. The light-colored rocks in the main range are Topatopa, the reddish rocks in front of them Sespe, and the shales along the lower hills, forming the foundation for the terrace, are Vaqueros and later beds of the Monterey group.