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Geology of the National Parks

GEOLOGY OF OLYMPIC NATIONAL PARK: PART Il NOTES ON THE GEOLOGY

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Cameron Creek

STOP 4: Cameron Basin

Just below Grand Pass and northeast of the trail are slabs of sandstone with a bumpy, cobblestonelike surface (fig. FT8). These

Load casts near Grand Pass
Fig. FT 8. Lumps (loadcasts} on the bottom of an upsidedown sandstone bed. The trail to Grand Pass crosses the photo in the middle foreground.

features form when sand is deposited on mud in the ocean bottom and differential settling of the sand into the mud forms bowl-like depressions filled with sand. The outcrops here are the bottom of the sandstone bed that has turned almost completely upside down.

The upper part of Cameron Basin is a spectacular example of a glacial cirque. The glaciers are gone, but their work is seen everywhere in rounded knobs and ridges, smoothed and striated rock bosses, long lateral moraines running down the valley, and even fresh, barren terminal moraines draped across the head of the valley below small patches of ice (fig. FT 9). A hike to the summit of the ridge to the east of the basin brings the glaciophile a view of the still-active Cameron Glaciers, more impressive than the ice relicts above the main basin.

At Cameron Pass, the contrast between the precipitous, recently glaciated north side of the ridge and the gentle south side is particularly conspicuous (fig. FT 10). If the south side was ever chewed into by glaciers, it was so long ago that the slow processes of weathering and rock and soil creep have long since erased the marks.

West Cameron Glacier
Fig. FT 9. West Cameron Glacier above moraine. In the foreground are glacially grooved and rounded outcrops showing that the valley was carved by a mightier glacier.
Remains of glaciers and their marks in Cameron Basin.
Fig. FT 10. Remains of glaciers and their marks in Cameron Basin. Note moraines left of glacier remnant. The contrast between the north and south sides of the ridge is well shown. The curved dark streak labeled RTD is a large depression formed by deep creep on the south side Aerial photo, looking south, by Austin Post.

On to Stop 5. Deer Park Road

Material in this site has been adapted from Guide to the Geology of Olympic National Park by Rowland W. Tabor, of the USGS. It is published by The Northwest Interpretive Association, Seattle.

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