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

MAIN LINE FROM MEDFORD SOUTHWARD.

Southeast of Medford the valley narrows, and at Talent low foothills of Cretaceous rocks are close to the railroad. The gravels formerly worked in the placer mines seen along here on the right (southwest) are for the most part of Quaternary age. Some gold, however, has been obtained from a Cretaceous conglomerate whose pebbles were derived directly from the still older rocks on which the conglomerate rests. The best known of these placers are those of the Forty-nine group, near Phoenix, which have yielded not only much gold but also a number of Cretaceous fossils. The older rocks on which the Cretaceous conglomerate rests are possibly Paleozoic. Farther south, in the neighborhood of Ashland, these rocks are succeeded along the railroad by a granular igneous rock (quartz diorite) resembling granite.

By looking ahead from a point near Ashland the traveler may see a bold rock, Pilot Knob, in the Siskiyou Mountains (a part of the Klamath Mountains). In early days this knob, which stands more than 6,000 feet above the sea, guided immigrants to the pass to California now utilized by the railroad.

Ashland, which passengers generally remember as the fresh-fruit station, is the center of a great peach country and took the prize for peaches at the Chicago Exposition. Pears also are being increasingly grown in this region. Orchards are being rapidly extended southward and westward over the lower slopes of the mountains facing the morning sun. Behind them rise the forested spurs of the Siskiyou Mountains, culminating in Siskiyou Peak (7,662 feet) and Sterling Peak (7,377 feet), which carry snow as late as July.

Near Ashland the crumbling quartz diorite is well exposed, together with sandstones and shales of Cretaceous age. To the northeast rises Grizzly Peak (6,000 feet), a pile of lava flows, under which, as may he seen on the gentle slopes near Bear Creek, are sedimentary rocks that contain some beds of coal and fossil plants, probably of Eocene age. The Eocene plants of the Cascade Range are described below by F. H. Knowlton.¹

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¹In the vicinity of Ashland and Medford there has been found a fossil flora which is not only totally different from that of Jurassic time but is also different from the living flora of Oregon. That this flora is very unlike the Jurassic flora is not surprising in view of its much later age (probably upper Eocene, Tertiary), which makes it many millions of years younger—in fact, a thing of yesterday as geologic time is measured.

The Ashland fossil flora is a small one, comprising only about 15 forms belonging to perhaps 10 types. Among them is a small fern with delicate, deeply cut fronds. There is also a Sequoia of the same type as the famous redwood of the Coast Range and probably a direct ancestor of it, together with a pine of the well-known white pine type, with its leaves in clusters of five. Among the dicotyledons or deciduous trees there is a well-marked species of alder, a chestnut with the usual sharply toothed leaves, at least four kinds of oak, an elm, a spice bush (Benzoin), and a leaf that is doubtfully regarded as belonging to a fig.

A flora which is of the same type and hence presumably of about the same age as this one is found in the rocks of northern California, especially about the big bend of Pit River and on Little Cow Creek east of Redding. These floras are evidently closely related to the plants that lived during the period when certain of the gold-bearing gravels of the Sierra Nevada in California were being deposited. The geologic age of these gravels has been determined in part by the aid of the fossil plants.

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On leaving Ashland the train begins to climb the Siskiyou Mountains, which form the divide between the Rogue and Klamath river basins. The pass is 2,235 feet above Ashland and the ascent is made by a 3.3 per cent grade—that is, at the rate of 174.2 feet to the mile. This average grade is maintained for nearly 30 miles. Shales, sandstones, and conglomerates of Cretaceous age are exposed along the railroad for more than 10 miles beyond Ashland, except a short distance beyond milepost 442, where some of the underlying older (Paleozoic) rocks appear. The Cretaceous rocks continue beyond the first great curve in the railroad line to a point near milepost 416, where an intrusive mass of granodiorite appears and continues to Siskiyou, the summit station. Beyond the second great curve, at milepost 415, there are good views of the valley left behind and of the Cascade Range.

At Siskiyou station the Pacific Highway, which crosses the summit farther east, near Pilot Knob, is near by on the left. Here on September 29, 1841, the Wilkes exploring party crossed the mountain, which was then the boundary between the United States and Mexico. Pilot Knob was named Emmons Peak by Wilkes, after the officer in charge of the party. At Siskiyou the railroad enters a tunnel 3,108 feet long, which passes about 500 feet below the summit. The rock near by is quartz diorite, and this is succeeded by a darker igneous rock (andesite) through which the tunnel has been driven and which, as will be seen farther south, is erupted through sediments of Cretaceous age. Soon after emerging from the tunnel into the drainage basin of Klamath River the traveler obtains his first view of Mount Shasta, one of the finest and most imposing of the snow-capped peaks of the Pacific coast. At milepost 410 Pilot Knob appears on the left (east).

At Colestin, about a mile beyond the end of the tunnel, a modest hostelry has been built near a good spring of effervescent chalybeate water. With its mountain surroundings, a delightful summer climate, and good hunting, this place is likely to be more frequented as its attractions become known.

In the descent from Colestin to Hilt (Cole) and thence to Hornbrook the train passes almost continuous exposures of Cretaceous sedimentary beds cut at many places by intruded igneous rocks. Some at least of these igneous rocks are tilted and faulted as much as the sedimentary rocks and consequently may be older than most of the lavas of the Cascade Range, which, as a rule, lie in nearly horizontal attitudes.

Before reaching Cole station, at 403.2 miles from San Francisco, the railroad crosses the line between Oregon and California.