August 16 (1976, 1979, 1983, 2000)
North Fork American from the air ~
Glacial evidence in the N. Fk. Canyon

8/16/76 ~ another fresh cool breezy day. hours after sunrise mandala window prints across the floor with trembling oak leaves. moon nearly full. yesterday i drove up to blue canyon airport and met tim ~ we went flying in his ercoupe, up the north fork canyon, across the sierra crest to truckee, where we landed and hung out for a while. then back by way of donner pass and the n. fk. canyon. it was very enjoyable and interesting. the enormous rockslides below snow mountain, waterfalls of the royal gorge, columnar basalt (andesite?) of devils peak ~ beautiful.


yesterday afternoon, steve came out and we played guitar for hours. then out to lovers leap late at night with big moon, [...] sitting on the cliff-around-the-corner.”

[Russell Towle's journal]

8/16/79 […] jon was given three red-tailed hawk babies whose nest tree had been felled by loggers. they are eating liver. ron la lande has one now.”

[Russell Towle's journal]

8/16/83 [...] Wonderful cumulonimbus clouds lofted up over the high country [...]

Some kind of wiring snafu in my car forced me to push start it when I came home. I read Mommson for about an hour [...] grabbed the flashlight, and at 11:00 PM or thereabouts went out to the tunnel for the fifth round of hydraulicking of the day.”

[Russell Towle's journal]

Date: Wed, 16 Aug 2000 07:02:52 -0800
To: Dave_Lawler
From: Russell Towle
Subject: glaciers

Hi Dave,

I did some exploring out on Sawtooth Ridge last Sunday, finally making it out to the old Helester Point lookout, about two miles southwest of I.T. Coffin's Big Spring Mine, and then I followed the ridge on foot another mile southwest. This ridge was subjected to enough erosion to remove most of its volcanic cap, so it does not have an even summit but rises and falls into passes and summits, with volcanics preserved on some of the nost northeasterly summits. The Shoo Fly is exposed on the crest at Helester Point (one of the summits) and I saw no sign of volcanic sequences on the summits southwest of Helester Point.

I did, however, note a thin scattering of glacial debris on the summit. There were rounded boulders of various rock types, but most significantly, some granitoid boulders from miles away, perhaps the South Yuba basin. These had a distinctly weathered appearance and may predate the last glacial advance. A line produced to the northwest, at right angles to the canyons and parallel to the Sierra crest, from the southwesternmost point I saw these granitoid boulders, would intersect Drum Forebay. There was a summit a little ways farther southwest which might well have had more of these granitoid glacial artifacts, but I did not walk that far.

This glacial debris is in accord with my landscape renderings of the adjacent portions of the main North Fork canyon, which look to be glacially smoothed. In fact, taking the debris on Sawtooth Ridge, and the smoothing in the renderings, both into account, it seems likely enough that at glacial maxima, the North Fork's valley glacier must have extended southwest to the vicinity of Humbug Canyon. In fact, Humbug Canyon seems quite unnaturally deep and large, with respect to the size of its drainage basin, and I think that it must have received glacial ice at its head, which had spilled over onto the Foresthill Divide from the main canyon to the northeast. This would be analogous to the case of, say, Blue Canyon, the upper basin of which would have been below the firn line, but which nevertheless received ice from the South Yuba icefield; the two nearby lobes of which, flowing down Bear Valley, and the North Fork of the North Fork American, filled up both canyons and overtopped the dividing ridge, allowing ice to extend southwest to the head of Blue Canyon itself.

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