Volume 8 No. 3 – September 1, 1935All material courtesy of the National Park Service.These publications can also be found at http://npshistory.com/Nature Notes is produced by the National Park Service. © 1935 |
Discovery of the Fumaroles at the Pinnacles, Wheeler Canyon
On August 16th, the writer of this article, accompanied by David Griggs, geologist of Harvard University and Fred Hoffsteld, E. C. W. technical assistant, made a study of the Pinnacles area in Wheeler Canyon, a tributary of Sand Creek, near the East Entrance to Crater Lake National Park.
Looking upward from the bottom of the canyon we noted a reddish band some three feet thick near the top of the west wall just below the pumice filling and at the upper limits of the gray buff horizon in which the pinnacles occur. This unusual degree of oxidation called for some special explanation since it is not present in some other localities where the same valley filling has been cut into by the stream.
Just as we reached the top of the canyon wall, Mr. Griggs, who was ahead, pausing for a few minutes to rest, placed his hand on a small cone-shaped projection of the tuff which at this point seemed to resemble a mass of re-cemented rubble, and exclaimed, “Ho, what have we here?” As we looked it over more carefully we saw at once that we had an old fumarole to deal with. Examining it critically, we saw that it had a cavity inside resembling a small assay muffle furnace, though not just the shape of one. Evidences of baking, incipient fusion, oxidation of the walls, and deposition of a whitish to yellow encrustation on the interior and even of kaolinization of the rock fragments, with a small nearly circular opening at the top, proved conclusively that this was indeed a fumarole whose activity had long since ceased.
This particular fumarole is about two feet in diameter in its widest part and of course narrows at the top to the size of the opening of about six inches. It is about two feet high and is fed by a tubular opening from below.
Looking about us, we found many more of these gas and steam vents. They all appeared to be in the upper portion of the tuff at the red horizon.
Further scrutiny of this locality revealed the fact that some of the pinnacles were merely the indurated chimneys or ducts leading up to the vents at the top. In other places nearby we saw some tubular fumaroles following the shrinkage joint cracks in the tuff. These various vents varied in size from six inches to two or three feet in diameter.
The similarity of these to fumaroles in the great hot sand-flow of Katmai in Alaska was noted by Mr. Griggs, who had seen them while with his father, Professor Robert Griggs, in the Valley of Ten Thousand Smokes.
The significance of these extinct fumaroles in Wheeler Canyon is at once apparent when the impression has been given, though not directly so stated, by Diller, that glacio-fluvial material predominated in these valleys radiating from Crater Lake. Diller, indeed, mentioned briefly the jointed tuffe in Annie Creek Canyon, but did not note the true character of them and apparently did not see the old fumaroles.
The finding of so much pyroclastic material which was in a quite hot condition, whether it feel as showers of ash or flowed out as a sand-flow, lends additional support to the explosion theory of the origin of Crater Lake.
This discovery in Wheeler Canyon has led to the finding of other localities where similar phenomena may be noted. Ranger Naturalist Carl E. Dutton has found a rather large one, approximately eight feet in diameter in a tributary gully of Llao’s Hallway in Whitehorse Creek, and a number of once hot spots can be noted in the road cuts of the Park.
Considering all these recent fumarole finds and the charred logs and buried trees, some quite carbonized, reported within the last few years, we have a piling up of interesting data which will shortly lead to a complete solution, this writer believes, of the problem which has long kept geologists in controversy.
Judging from the number of these fumaroles within the limited area studied, the number of them throughout the entire valley must have compared favorably with those in the Valley of Ten Thousand Smokes. What a spectacle they must have presented at the time of their activity! In all likelihood, no human being could have looked upon this scene as it probably long antedated the appearance of man in America and furthermore much of this country was mantled by snow and ice.
Diagrammatic Section of the West Wall of Wheeler Canyon at the Pinnacles, Crater Lake National Park
