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

SHEET No. 5A (click on image for an enlargement in a new window)

The village of San Ardo (see sheet 5A, p. 122) is surrounded by a wheat and stock country which includes the rolling low hills along the river. An exposure of the Santa Margarita formation begins about 6 miles south of San Ardo and extends in a northwesterly direction to a point on the west edge of the valley immediately opposite San Ardo. This strip of Santa Margarita beds consists of white sandstone that at several localities contains fossils. The geologic structure immediately west of San Ardo is complex. The hills for several miles back from the river on the west side are composed of Monterey shale.

Three miles northwest of San Ardo the Paso Robles gravels on the east side of the valley give place to sandstones of the Santa Margarita formation, which occupy an area of many square miles extending in a northeasterly direction from San Lucas. Fossils, including numerous sea urchins and oysters, occur at several points throughout the area. The Santa Lucia Range, which bounds Salinas Valley on the southwest, culminates in Santa Lucia Peak and Vaquero Peak, in the region west of San Lucas. The upper slopes of these mountains consist of coarse heavy-bedded fossiliferous Vaqueros sandstone dipping toward the valley. This sandstone, toward the railroad, is overlain by the upper formation of the Monterey group. Along the northeast edge of Salinas Valley the Monterey in turn is overlain by the Paso Robles formation, which either rests directly on the Monterey or at some places on intervening beds of the Santa Margarita formation.

Extending north for 3 miles and west for 4 or 5 miles from San Lucas is a gravel terrace probably deposited by the river at an earlier stage in its history.

King City is a shipping point for gypsum obtained from the hills, about 15 miles to the north-northeast. At Elsa, 3 miles farther north, the raising of sugar beets is an important industry. The Paso Robles gravels continue to occupy both sides of the Salinas Valley to a point within 3 miles of Metz. From Chalone Creek, which is crossed at Metz, northward the main Gabilan Range becomes more rugged and consists chiefly of granite with some schist and crystalline limestone. This part of the range, which has been little studied, contains some metalliferous deposits, especially ores of quicksilver.

At milepost 147 the railroad leaves Salinas River and surmounts a terrace which borders the river for some miles. The deposits forming this terrace are comparable with those near San Lucas.

Soledad (so-lay-dahd', Spanish for solitude) is built on a fertile plain which forms part of the terrace just mentioned. From the town may be had fine views of the valley and bordering mountains, and the vicinity affords some delightful drives. Across the river are the ruins of the mission church built in 1791. A stage runs from Soledad southwest 8 miles to Paraiso Hot Springs, at an altitude of 1,400 feet in the Santa Lucia Range. About 14 miles northeast of Soledad are The Pinnacles (Pl. XXX, p. 124), picturesque masses that have been sculptured by erosion from some rock whose character and geologic age have not been ascertained. The prominent peaks 6 or 7 miles east of Soledad are the Chalone Peaks, which are composed of marbles and other crystalline rocks that are probably older than any others in the Coast Range. North of them is an area of rocks in which copper and quicksilver occur. Flanking these peaks and extending northward along the northeast side of Salinas Valley are some hills of moderate height composed partly of sandstone.

PLATE XXX—THE PINNACLES, 12 MILES NORTHEAST OF SOLEDAD CAL. Formed by erosion of fragmental rocks.

On the west side of the Salinas Valley, opposite Soledad and Camphora, are some old alluvial fans that merge with the terrace deposits along the river. Recent erosion has cut trenches in some of these fans, but as a rule they stand out as nearly perfect examples of this type of stream deposit.

Along this part of Salinas Valley the same contact observed farther south persists; the mountain slope on the northeast is comparatively gentle, but that on the southwest is steep. The southwest slope, as previously noted, is probably a fault scarp or fault cliff, worn back and cut into by erosion.

Beyond Gonzales (gohn-sah'lace), in the neighborhood of Chualar (chwa-lar'), the valley gradually widens northwestward, toward Monterey Bay. Great quantities of alfalfa hay and grain are produced in this vicinity. The terraces found all along the Salinas Valley from Templeton northward are here well developed and grow broader toward the mouth of the river.

The town of Salinas (Spanish for salt pits) is the center of a large beet-sugar industry. Besides sugar beets, beans are extensively grown in this region, especially near the coast. Opposite Salinas the river flows at the extreme west edge of the valley.

Del Monte Junction lies but a few miles from the mouth of Salinas River and Monterey Bay. A branch line, over which pass through trains to and from San Francisco, runs southwest from this junction to Del Monte, Monterey, and Pacific Grove.¹

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¹The Hotel Del Monte, in grounds world-famous for their beauty, is situated on one of the most charming and interesting parts of the whole California coast. Near by are the combinations of rocks, sea, woodland, and hills such as delight an artist. Old buildings and associations appeal to the student of early California history. There are ample facilities and opportunities for the pursuit of sport of many kinds. Finally, the region is of exceptional geologic interest and is the type locality of the white shale of the Monterey group. This shale, although soft when quarried, hardens on exposure and withstands the sea air without crumbling.

Monterey, although visited and named by the Spaniards in 1602, was not permanently settled until 1770. In that year Gaspar de Portolá, the first governor of Alta California, arrived by land, and Padre Junípero Serra, of the Franciscans, a few days later by sea. Serra founded at Monterey his first mission in Upper California. The mission at Carmel, where Serra lived and died, was founded the next year. San Carlos Church, Monterey (Pl. XXIX, B, p. 119), is sometimes confused with the San Carlos mission at Carmel. Commodore Sloat landed at Monterey July 7, 1846, and took possession for the United States. A monument to him and one to Serra stand in the Presidio. Monterey was the first capital of California, and in Colton Hall the first constitutional convention was held September 1, 1849. An association of more recent date that will endear the place to many is that here for a time lived Robert Louis Stevenson.

Monterey is the terminus of a pipe line from the Coalinga oil field, in the San Joaquin Valley, and from 12,000 to 15,000 barrels of oil is pumped through this line daily.

Soundings by the United States Coast and Geodetic Survey have shown that a deep depression extends across the bottom of the comparatively shallow Monterey Bay out to the steep submarine slope that marks the real boundary between continent and ocean. Some geologists have interpreted this depression as a valley of erosion cut by Salinas River when the land stood higher than at present and when the bottom of the bay was dry land. Prof. A. C. Lawson, however, has maintained that a similar submarine valley, in Carmel Bay south of Monterey, which is not quite in line with the present valley of Carmel River, is probably a structural sag or syncline and not an erosion valley at all. He can find no evidence of recent uplift of this part of the coast sufficient to have enabled the river to cut a valley across what is now the bottom of the bay.

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Some terrace deposits may be seen east of Del Monte Junction. They extend northward to the edge of Pajaro Valley, the surface apparently rising to the north. The railroad traverses a lower plain terrace descending from 16 feet at Del Monte Junction to 2 feet at Elkhorn station, beyond which it turns up a little valley cut by Elkhorn Creek in the marine terrace deposits. After crossing Elkborn Slough and bearing to the left between some low hills, the railroad emerges, at about milepost 101, in the Pajaro Valley (pah'ha-ro, Spanish for bird).