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

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

The material of the terminal moraine southeast of Olympia is best exposed in the area surrounding Patterson Lake. The railway cuts are not deep, however, and are therefore not very satisfactory to the geologic observer. The open prairies on the glacial outwash plain (that is, the plain formed by gravel washed from the front of the glacier) begin at Kyro. They present a sharp contrast with the dense forests around them and are probably due to some peculiarity of soil or drainage that is unfavorable to forest growth. Several miles beyond is Chambers Prairie, which is 2 miles north of the railroad station of the same name. (See sheet 2, p. 24.) From this prairie excellent views may be obtained of Mount Rainier, in the rear, to the left, and of the Black Hills, ahead, to the right. Just before Plumb is reached there is another fine view of Mount Rainier, across a meadow.

At milepost 38 the railway enters Rocky Prairie, which is notable for its curious mounds. The origin of these mounds has been fully discussed by Prof. J. H. Bretz, of the University of Chicago, who concludes that they are not the result of erosion, as some have thought, but that the gravel of which they are composed was deposited in hummocks. Similar mounds are abundant on some other prairies.

After traversing another belt of terminal moraine and of hills composed largely of Tertiary shales the railway enters Tenino, which stands near the end of a projecting spur of the Cascade Range. On the right, near the station, is a quarry of a sandstone that is widely known to builders in the Northwest as the "Tenino sandstone." It is generally fine grained, well cemented, and easily worked, and has the valuable property of hardening after being quarried. The high school and Trinity Church in Seattle are built of this sandstone. The rock is of Eocene age. About a mile north of Tenino, near the old line of the Northern Pacific, is a large quarry in the same sandstone, from which the Government has obtained rock for the Grays Harbor jetty.

The Puget Sound glacier, of the Vashon substage, is believed to have had its southern boundary, at its time of greatest extension, near the line where the prairies end against the timbered hills south of the town. There is, however, no terminal moraine marking this limit for some miles east or west of Tenino.

At Tenino the railway is joined by the old line of the Northern Pacific from Tacoma. This line passes through much prairie country on the great outwash gravel plain formed by the melting of the Puget Sound glacier. A few miles north of Hillhurst and at Yelm the traveler may enjoy fine views of Mount Rainier.

As Bucoda is approached the valley widens. The railway crosses Skookumchuck River (Chinook jargon for "mighty water") and runs between bluffs of coal-bearing Eocene sandstone on the left and the river on the right. Just south of Hannaford Creek the beds in the bright-red cliff on the left stand vertical. The brilliant colors have the effect of a burned coal bed. Waters flowing from the Puget Sound glacier found an outlet down this valley as far as Centralia and thence went northwestward by way of the Chehalis River valley.

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¹Distances by the old line are given for stations beyond Tenino, and to get the distance actually traveled from Seattle by the new line 6 miles should be added.

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Centralia, about a mile above the mouth of the Skookumchuck, is an important railway junction and the center of a large lumber industry. The town is also becoming a coal-mining center, and much attention is given to dairying and to the growing of small fruits, especially strawberries. The coal-bearing rocks, of Eocene age, lie east of the town. The beds to the west (Astoria shale) are Oligocene, and are succeeded by still younger formations toward the coast.

Below Centralia the Skookumchuck enters the broad valley of the Chehalis, a river which drains a section of the Cascade Range and flows across the Coast Range to the Pacific at Grays Harbor. Two railway lines, a branch of the Northern Pacific and a line of the Oregon-Washington Railroad & Navigation Co., connect Centralia with the coast by way of Chehalis Valley.

Chehalis is the center of a large dairying district and has a condensed-milk factory. A branch line runs west from this place to South Bend. The State Training School stands on a terrace formed by gravel with soft decomposed pebbles, which is well exposed in several street cuttings a few blocks west of the railway station and at many other points farther down Chehalis River, especially at Satsop. These gravels were deposited during the early part of the Pleistocene epoch by the floods from the melting glaciers.

South of Chehalis the river is joined by Newaukum River. The valley at their confluence is broad and fertile and contains many thriving farms, chiefly on the left. A group of yellow monkey flower (Mimulus) brightens the wayside in spring and summer. Other plants likely to attract attention are the thimbleberry, with its white blossoms;, the salmonberry, with its yellow fruit; the pink freweed; the white, plumose, gracefully pendant ocean spray, or arrowwood (Sericotheca discolor, Pl. V, p. 17); and other forms growing among larger plants on the wooded slopes. In the more open ground the almost omnipresent dandelion in June, with its fluffy crowns of seeds, the purple lupine, the red and white clover, the white yarrow, and a host of other flowers give the beauty of varied coloring to the views in this forest land.

PLATE V.—OCEAN SPRAY (SERICOTHECA DISCOLOR), A COMMON FLOWER IN WASHINGTON. Sometimes called arrowwood, because the branches ore used hy the Indians in making arrows. Photograph by Barnes, Parkland, Wash.

From Seattle to Portland the great forests of Washington are almost continuous. The exceptions are the so-called prairies of the outwash gravel plains; the great stretches, bristling with the blackened trunk of many a forest monarch, which the lumbermen leave in their wake; and the long alluvial valleys which the farmer has cleared and tills. Alder and maple are the usual successors to the firs in the valleys.

Beyond Chehalis the railway gradually ascends through shallow cuts in Eocene sandstone and early Pleistocene gravel to Napavine, situated near the crest of a low east-west divide (450 feet above sea level) that separates Chehalis River from the Cowlitz, a tributary of the Columbia. The broad surface of the divide is the level top of an exentsive deposit of gravel that is well exposed in the cuts along the railway. In this locality the gravel consists largely of volcanic materials, the white quartz pebbles that are so common in many gravels being absent. About 3 miles beyond Napavine, near Evaline, may be seen the brownish Eocene sandstone which underlies the gravel.

The railway crosses Olequa Creek, along which is a well-developed bench or terrace eroded in the same gravel formation that was seen near Napavine. A similar terrace, at a corresponding height above the stream, is a prominent feature of the Cowlitz, Willapa, and other valleys in southwestern Washington. A bluff of the same gravels, here 150 feet in thickness and overlying Oligocene beds, appears on the left as Winlock is entered.

Winlock is commonly known as "Bungalow Town" and the station has been built in that style. About 3 miles beyond Winlock the valley opens and on the right a fine view is obtained of Abernathy Mountain, a spur of the Coast Range. On the left are some remarkably tall alders with a background of firs.

Near Vader station are the ovens, which are supplied by clay obtained near by. A mile beyond the town, on the right, is a small gas plant. The gas is made from the slabs rejected by the adjacent sawmill and is supplied to the town at the rate of $3 a month for five lights and a kitchen stove. The salable by-products of the gas plant are pyrogallic acid, creosote, tar, and charcoal.

Olequa Creek is again crossed and the train enters a short gorge. On the left, by looking ahead down the gorge, the traveler may get a fine view of the snow-covered top of Mount St. Helens, standing above deep-green forests of fir. Nearer at hand, on the left, a bluff exposes a sheet of lava overlying Eocene shales,¹ and on the right are Pleistocene sands.

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¹This is the region of the type section of the Olequa formation, described by Arnold and Hannibal as extending from the Ewing ranch, 2 miles above Little Falls [Vader], southward down Olequa Creek to Olequa, a distance of 5-1/2 miles.

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Olequa Creek joins the Cowlitz, on the left, at Olequa station. Some hop fields and hop dryers are visible up the Cowlitz. On the left at the end of the bridge a bluff of columnar basalt (lava) overlies Eocene shales, and the railway passes through a deep cut in this basalt that resembles the Bergen Hill cut, near New York. At the south end of the cut, on the left, the Eocene shales are well exposed. Much of the lava of this region was probably poured out at intervals over the sea bottom while the sediments that were later consolidated into sandstones and shales were accumulating, the lava thus becoming interbedded with the coal-bearing Eocene strata. Later horizontal sheets of lava overlie the tilted coal-bearing beds near the volcano St. Helens, from which they issued, but these later lava beds, although some of them probably extend for a long distance west of the volcano, are not visible from the railway.

Toutle River is crossed near its junction with the Cowlitz, and that river, bearing numerous log rafts, may now be seen at many places on the right-hand side of the railway.

At Castle Rock frost is rare. Here are extensive farms among the low-rounded hills of the region and some small orchards of prunes, cherries, and apples. The railway cuts near Castle Rock expose 60 feet of stratified light-gray sand, forming a terrace whose top has an elevation of 120 feet above the sea.