... i've gone to towle's hole* the past few days and swam. carried two tires and all the minor trash out. for the second year in a row someone has smashed exposures of water-polished magnesite in the serpentine matrix along one side of the swimming hole.”
[Russell Towle's journal]
[ * Note: "Towle's Hole", a formerly popular swimming hole on Canyon Creek downstream of the Casa Loma bridge, was named because of its proximity to the historic town of Towle, located between that spot and the town of Alta. The three Towle Brothers, well known in Dutch Flat history, had based their extensive timber business there. “Towle's Hole” is in a spot where the creek crosses private property, and in the early 1980s a house was built on the parcel, blocking off public access to that local treasure. Most remnants of the town of Towle were erased by the construction of Interstate 80. Incidentally, Russell was not directly descended from these Towle's, but both family lines can be traced back to a common lineage in New England. —Gay ]
“6/8/87 I am depressed today, full of a sense of failure about my efforts to protect the North Fork Canyon, full of anxiety about money matters...”
[Russell Towle's journal ]
Date: Fri, 8 Jun 2001 14:55:40 -0800
From: Russell Towle
Subject: TNF LWCF
|The Channel 10 video crew, working hard at Big Valley Bluff|
June 8, 2001.
|Blooming at Big Valley Bluff, June 8. 2001|
Naked or Wild Buckwheat
Anyway, I got some good fluttering slates but I don't know if they'll show up on Rob's video.
|The Sierra Crest peaks south of Donner Pass as seen looking east up the North|
Fork American River canyon from the Big Vally Bluff clifftop, June 8, 2001.
Date: Sat, 8 Jun 2002 18:27:05 -0800
From: Russell Towle
Subject: Drum Powerhouse & the Miners Ditch
It did not fizz; I crushed it into a powder, added vinegar, added lemon juice and Vitamin C, and, it did not fizz.
I regularly surf the internet looking for information on specific geological subjects, among them, the pattern I have perceived, of heavily cemented glacial outwash gravels where Sierran canyons (or any canyon whatsoever) cross serpentine belts. There is a complete absence of information about this pattern on the internet, with the exception of my own web pages.
A few days ago, tho, I found a fascinating page about the "Josephine Ophiolite," a suite of ultramafic rocks including serpentine, near the border between Oregon and California. See http://jersey.uoregon.edu/~mstrick/GeoTours/Josephine%20Ophiolite/JoOphiolite.html and, if you like geology, you're in for a treat. The author, Michael Strickler, is a professor up there, and quite the expert on these types of rock. So I emailed him with a query about cemented gravels in the canyons which cut the Josephine Ophiolite. He has kindly responded, in the negative as to his own personal experience of such cemented gravels, but suggesting that the cementing agent might be calcium, and further, that with dilute hydrochloric acid, I could test the cemented gravels myself for the presence of calcium (it fizzes in acid).
I drove out Drum Powerhouse Road this morning to collect samples of cemented outwash from the ferny old mines below the dam. Samples collected, I decided to explore upstream from the powerhouse, and scramble up to the Miners Ditch, and follow it east and upstream. Immediately east of the powerhouse are several private residences, occupied, I should think, by PG&E employees.
I noted that directly across the river from the powerhouse, a small wedge of serpentine was exposed, several hundred feet high, and likewise several hundred feet across at the base. At river level, there is a large shelf of cemented outwash gravels. A huge granite boulder is embedded in them. This mass of natural cement receives the force and fury of the water discharged from the Pelton wheels inside the powerhouse. It is a striking example of the correlation between serpentine and cemented outwash.
This little wedge of serpentine, lying east of the black slates which are east of the main Melones Fault, throws even more suspicion upon these intervening black slates; now I have even more doubt that these slates are part of the main Shoo Fly Complex rocks, east of the serpentine.
I was prepared to ask permission to cross if anyone was about, but all was quiet. So I continued past and climbed up a sort of road/overflow channel thing leading up to one of the penstocks. This turned into a steep cement-lined chute below the penstock, a six-foot-diameter pipe. It was barely walkable. At a certain point, about 200 feet above river level, a set of wooden stairs led up to a set of ultra-heavy-duty steel stairs, which paralleled the penstock.
At the beginning of these stairs I looked about on the nearby slopes for any trace of the Miners Ditch, saw no trace, but decided to leave the penstock and thrash around until I found the ditch. This worked out well, tho it was a steep climb of another hundred feet to reach it. It is bolstered by massive dry-laid stone walls in this section, and quite mossy and shady, with large Douglas Fir trees dominating the forest. i followed the ditch east, imagining that I had a chance, considering the relative lack of undergrowth, to make good time, and possibly, reach the place where the ditch once drew water from the Bear river. According to my calculations, that would be about three miles upstream.
However, my hopes were soon dashed, as I met a steep-walled ravine, where the ditch had once crossed on a wooden flume. A sheer cliff of about a hundred feet barred my way. I dropped down off the ditch into the forest and found a major game trail, possibly an old human trail, crossing the ravine lower down, and followed it east and upcanyon. For a while it seemed like the remnants of a smaller ditch, but I found myself losing elevation rapidly and was soon down at the river. Here, large piles of mossy boulders showed that the 49ers or, at least, 19th-century gold miners, had worked the glacial outwash deposits here (which, since not in serpentine, are uncemented). I found myself on a gravel bar, with a ducked trail leading to it from downstream. Across the river, a boulder of granite more than ten feet across lay at water's edge. This gave me some pause.
A glacier has little problem moving boulders this size around; but can they be so easily transported in volumes of glacial outwash? Did this boulder hark back to a time when glacial ice came all the way down to Drum? Well, possibly. On the other hand, in ravines with steeper gradients, on the east side of the Sierra, boulders of granite which make this one look like a pebble have indeed been transported in glacial outwash. If you think about it, just as a boulder weighs less in the water than it does in open air, how much less will it weigh, enmeshed in a slurry of water and sand and clay and gravel; in glacial outwash? Imagine as well, that while the glaciers were receding, and the last Ice Age was ending, there may have been episodes of intense melting which vastly increased the amount of meltwater coming out of the glacier, farther up the bear river canyon.
At any rate. I followed the ducked trail downstream, but there is no passage at river level, and the trail leads into the back yard of a house with a large, barking Rottweiler. I called out a "Hello!" but no one appeared, so thinking disgression the better part of valor, I climbed back up to the little trail in the woods and followed it west to the penstock, then on up the steep steel ladder in search of the Miners Ditch; no sign at all nearby, so just took a chance and happened to hit it dead on, not one inch too high or low. Soon I was back at the car.
Such was a visit to Drum Powerhouse. It would not be hard to return there and pick up the Miners Ditch east of the cliffy ravine, except, the house most key to one's passage, is not only occupied, but has a big guard dog. Incidentally, that part of the canyon looks very wild. A little ways upstream there were some huge rockslides in the January 1997 flood event. These likely erased parts of the Miners Ditch, as they did erase parts of the Pacific Turnpike, the South Yuba Canal, and the Towle Brothers narrow-gauge railroad roadbed.
|View eastward through Giant Gap from the HOUT (High Old Upriver Trail) |
June 8, 2005