Geological Survey Bulletin 581—B Oil and Gas in the Western Part of the Olympic Peninsula, Washington

ROCKS EXPOSED ALONG HOH RIVER.

Before the description of the rocks noted along Hoh River is given it seems proper to state that the writer did not visit all the exposures along this stream but only the more prominent ones that could be easily examined when traveling along the principal trail on the north side of the river valley. The stratigraphy and structure along this stream can best be studied from a canoe, but it was impossible, on account of the short time spent in this portion of the field, to make a careful study of the beds exposed in the river banks.

At location A, on the north side of Hoh River, about one-half mile from the ocean, beds of gray sandstone and sandy shale about 75 feet thick are exposed. These beds are much broken by joints and fractures and on account of the presence of many small faults dip at different angles and strike in different directions. They dip approximately 31° SW. and strike N. 55° W. At location B, on the south side of the river, in the SE. 1/4 sec. 21, T. 26 N., R. 13 W., there is an exposure 100 to 200 feet in length of yellowish-gray thin-bedded, somewhat micaceous sandstone, which dips 75° NW. and strikes about N. 25° E. At location C, on the south side of the river, about one-third of a mile southeast of location B, almost flat-lying beds of bluish sandy clay of Pleistocene age are exposed. At location D, just east of W. D. Hough's house on the south side of the river, a grayish-blue sandstone, which weathers yellow and which is soft when wet, dips 45° SW. and strikes N. 15° W. Another reading taken near by shows that the same bed dips 46° SW. and strikes N. 33° W. About 200 yards downstream from this locality, near an old log jam, bubbles continually rise to the surface of the water. It is possible that these bubbles are formed by escaping natural gas, but more probably they are due to air that has been carried into the water or to marsh gas. Some of the gas was collected, but an attempt to ignite it was unsuccessful. At location E, on the north side of the trail, about 2 miles east of Hoh post office, approximately in the SE. 1/4 sec. 15, T. 26 N., R. 13 W., 150 feet or more of poorly consolidated conglomerate is exposed. This conglomerate probably corresponds in age to the beds of similar clay and conglomerate of Pleistocene age noted in other parts of the area.

The rocks exposed in the shaft of the Lacy oil seep, situated about 2-1/2 miles northeast of Hoh post office, are reported to consist of soil, sandy clay, sand, gravel, and bowlders of Pleistocene and Recent ages. The larger pebbles and bowlders are a foot or more in diameter and increase in size with the depth of the shaft. Most of them are subangular or flat sided, suggesting glacial scouring. W. H. Abbott, who assisted in opening the shaft, stated that it was his opinion that when the water is removed from the shaft the maximum flow of oil is about 2 barrels a day. At the time this place was visited by the writer, in August, 1913, the shaft was full of water. A small amount of oil floating on the water was collected and sent to the laboratory of the Geological Survey, where it was analyzed. A discussion of the results of this analysis is given on pages 31, 32. Gas escaping from the shaft disturbed the water somewhat from time to time. The small amount of oil on top of the water in the shaft is explained by the theory that the weight of the water prevents the oil from flowing into the shaft.

Beds of yellowish-gray sandstone are poorly exposed for a short distance along the side of the trail at location F, near Anderson Creek, about 1 mile west of W. P. Elliott's house (formerly Pins post office). A fairly good reading obtained on this sandstone shows that it dips 70° N. and strikes N. 76° W. At location G, on the north side of the river and about 300 yards upstream from Elliott's house, gray sandstone and bluish-gray shale interbedded is exposed for 200 or 300 feet. About 200 yards east of Elliott's house there is a rather massive sandstone bed which contains some shale and is reported to contain coal in very thin lenses. The beds here dip at different angles, but the prevailing dip is about 86° W. and the strike N. 6° W. Farther east, at location H, on the same side of the river and one-half mile east of Elliott's house, beds of gray to chocolate sandstone and sandy shale are exposed. They dip 52° NE. and strike N. 50° W. These beds are somewhat broken by faults, and there is also evidence of the presence of small folds.

In secs. 27 and 28, T. 27 N., R. 12 W., Hoh River flows through a canyon 100 feet deep and 2 miles or more in length. At the eastern end the walls of the canyon are composed of yellowish-gray to bluish-gray sandstone, shale, and shaly sandstone. These rocks occur in about the proportion of 1 part of shale to 10 parts of sandstone. At location I, at the east end of the canyon, on the north side of the river, in the SW. 1/4 sec. 27, the beds of sandstone and shale were examined for one-third to one-half mile. They dip 56° N., strike N. 80° E., and consist of the same kind of rocks and same proportion as described above. About 1,000 feet downstream from, the upper end of the canyon the rocks consist of yellowish to chocolate-brown, very thin bedded sandstone and a little sandy shale. In the bed of a small brook about 200 feet north of the river the strata dip 32° NW. and strike N. 30° E. On the river's edge at the mouth of the same brook the beds consist of gray medium-bedded fine-grained, rather resistant sandstone, which dips 55° NE. and strikes N. 45° W. A small fault was observed between these two places. Possibly 50 to 100 feet downstream from the mouth of the brook the beds dip 55° NE. and strike N. 70° W. Between this locality and the mouth of the brook the strata are very much disturbed by small faults. About 100 feet farther downstream interbedded sandstone and carbonaceous shale, which dips 58° NW. and strikes N. 30° E. is exposed. The same distance farther downstream medium-bedded gray sandstone, dipping 63° NE. and striking N. 57° W., is exposed. Two hundred feet farther down the river sandstone similar in appearance to that last described dips 52° NE. and strikes N. 55° W. The last two dip and strike readings are very much alike and indicate that probably both were measured on the same fault block. At location J, on the north side of the river, near the mouth of a small creek near the center of sec. 26, T. 27 N., R. 12 W., gas is reported by the owner to be escaping from the edge of a circular spring of water. The water in this spring is said to have a milky-white color, like that at the Devils Mush Pot, a few miles farther up Hoh River, which is due to the action of gas in loosening and carrying up very fine sediment from the bottom of the inverted funnel-shaped hole.

At location K, about 1-1/2 miles farther upstream, on the south side of the river, near T. H. R. Schmidt's place, beds of massive sandstone and brownish chocolate-colored sandy shale, dipping 31° E. and striking N. 39° W., are exposed just below the mouth of a small stream that joins Hoh River from the south. This exposure, which consists of about 5 per cent shale and the remainder sandstone and sandy shale, is the only one along the river for a mile or more both up and downstream. Very small lenses of coal, which attain a maximum thickness of 2 inches and a maximum length of 6 inches, are included in a sandstone stratum about 4 feet in thickness. The coal, which has a bright luster, burns with a bituminous odor and yellow flame. A small, almost vertical fault, trending N. 65° E., cuts these rocks. The section measured at this place is as follows:

Section of rocks exposed at location K, near the center of sec. 25, T. 27 N., R. 12 W.

Rocks that may be exposed along Hoh River, between location K, near Schmidt's place, and location L, about 1-1/4 miles southwest from Spruce post office, on the south side of the river, were not examined, because on traversing the valley the trail which lies on the north side of the river and some distance from it was followed. The rocks over which the trail passes consist principally of clay, sand, and gravel, partly consolidated and partly loose, of Pleistocene and Recent ages. Along the trail from Schmidt's place to Spruce post office none of the older formations are exposed.

At location L, referred to above, a hard dark fine-grained medium-bedded sandstone, containing here and there near the top thin lenses of limestone, is exposed. Above the limestone the rocks consist of dark chocolate-brown iron-stained argillaceous sandstone, which has apparently been subjected to crushing forces, as it is now quite brittle and crumbles easily. The beds dip approximately 50° SE. and strike N. 40° E. At location M, about one-half mile farther east, in the vicinity of the mouth of Owl Creek, very hard dark fine-grained medium-bedded sandstone, with some dark hard fine-grained sandy shale in the western part of the outcrop, is exposed. It is rather difficult to obtain a reliable dip and strike reading at this place on account of the massiveness of the strata. However, the prevailing dip is about 75° NE. and the strike is N. 40° W. The Devils Mush Pot, described in detail on pages 29-30, and referred to in other parts of this paper, is situated at location N, about one-fourth of a mile farther northeast. It may be added here that the rocks surrounding the gas vent consist of gravel, sand, and clay of Recent age. As the "mush pot" is situated near the outcrop of the older rocks, at location M, and as this same formation outcrops to the east of this locality, it is reasonable to assume that the gas which escapes from this vent originates probably deep in the older rocks instead of those at the surface. In traversing the upper part of Hoh River above Spruce post office a recently completed trail, which lies on the north side of the river and in most places one-fourth to three-fourths of a mile from it, was followed, and hence no exposures were seen by the writer in this stream valley farther north than those just described in the vicinity of Spruce post office. It is reported that gas is escaping in small quantities at location O, which is a few hundred feet north of Hoh River and on the eastern edge of the area represented on Plate II (p. 78). This point, which is about 5 miles east of Spruce in the NE. 1/4 NE. 1/4 sec. 22, T. 27 N., R. 11 W., was visited by the writer, but no evidences of gas were noted.

It is believed, as has been stated in the beginning of the description of the rocks exposed along Hoh River, that many outcrops of rock in addition to those noted above can be seen along this stream, and that whenever more detailed work is to be done in this region it will be necessary for the geologist to traverse the river by means of a canoe and examine carefully every exposure, however small, as was done by the writer along the lower courses of Moclips, Queniult, Queets, and Clearwater rivers.

The strata exposed along the lower course of Hoh River between locations A and H are, with but little question, representative of the "supposed Cretaceous" rocks, whereas those beds exposed in the prominent canyon of the Hoh River in sees. 27 and 28, T. 27 N., R. 12 W., and from this locality east to location M, near Spruce, probably belong to the Clallam formation, of Oligocene and Miocene age, described by Arnold.¹ It is possible that those beds exposed at locations F, G, and H in the vicinity of Elliott's place (formerly Pins post office) may belong to the same formation. As stated previously, it was Arnold's opinion that the rocks exposed in the hills south of Bogachiel River belong to the Clallam formation. The hills referred to constitute the divide separating the drainage of the Bogachiel from that of Hoh River, and at no place east of range 13 are they more than 4 miles from the Hoh.

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¹Arnold, Ralph Geological reconnaissance of the coast of the Olympic Peninsula, Wash.: Geol. Soc. America Bull., vol. 17, pp. 461-462, 1906.

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Beds of Pleistocene age overlie the older formations unconformably and at one place along Hoh River (location C) bluish sandy clay, presumably of the same age, outcrops along the river bank. At no place along Hoh River did the writer note any evidence of "smell mud" and at but one locality (the Devils Mush Pot) is there any evidence of natural gas, except that reported at location J, on Billy Snell's land.