March 26 (1978, 2003 2005)
Geomorphology. Opportunity.

3/26/78   yesterday tim and valdemar and denise and dave came out and we went on a scramble down to the keyhole. saw a golden eagle, cañon wren, and many cliff swallows… on ledges near the keyhole there were abundant blue dicks ~ tritelochemma pulchella*  ~ in bloom, intermingled with lush soaproot and a couple of bush poppy also in bloom. many of the yellow-flowered umbellifers ~ lomatium sp.”

[Russell Towle's journal]

[Perhaps‘tritelochemma pulchella’ for blue dicks is an error. See:
http://en.wikipedia.org/wiki/Dichelostemma_capitatum#cite_note-0
and see the synonyms in the right sidebar of that page.  -Gay ]

The Opportunity

Date: Wed, 26 Mar 2003 19:09:37 -0800
To: North_Fork_Trails
From: Russell Towle
Subject: Gold Run

Hi all,

Patty McCleary, who has much experience with land acquisition projects and grant-writing, having worked for the Trust for Public Land and the Sierra Club, has very kindly written the text for a brochure about our proposed Gold Run land acquisitions.

For those new to this list, 800 acres within the historic Gold Run Diggings are now for sale. Much of this private land interfingers with BLM lands and is within a special "Gold Run Addition" to the North Fork American Wild & Scenic River "corridor."

I would be very pleased to hear any suggestions or corrections. I can think of one correction at once: Giant Gap is not just "popularly" so known, it is officially so known, as one can see on the Dutch Flat 7.5 minute quadrangle, and many old maps, the name dating back to 1849, I believe.

Patty's text is within the asterisks.

[2014 note: The property is STILL for sale... it remains a laudable goal to bring it into the public domain, which would complete the intention of Congress when the adjacent river section was designated for Wild and Scenic protection. Mercury contamination and other mining legacy hazards make acquisition of this land by the federal government impossible under current regulatory law, and also creates crippling liability issues for other potential purchasers—so the property remains in limbo. ] 

North Fork American
Giant Gap Wild and Scenic Corridor
Canyon Creek Project
…A few miles beyond, there suddenly opens on the gaze of the expectant traveler, the vision of The Great American Cañon -- by far the finest cañon of the entire Pacific Railroad. The suddeness of approach, and the grandeur of scene are so overpowering, that no pen, picture of language can give it adequate description. Two thousand feet below, flow the quiet waters of the American River. Westward is seen the chasm, where height and peak and summit hang loftily over the little vale.”

The Pacific Tourist, 1876 guidebook
THE OPPORTUNITY

The Public has an opportunity to complete the Wild and Scenic River corridor for the North Fork of the American River by acquiring key parcels totaling 1,000 acres located inside the boundaries of the North Fork of the American River Wild and Scenic Corridor.

The current landowners, Gold Run Properties (GRP) and other private landowners have declared their interest in selling their respective acre properties to the BLM.

WILD AND SCENIC DESIGNATION

The North Fork American River is one of three forks that make up the American River system. These rivers are major tributaries of the Sacramento River.

In 1978, a thirty-nine mile stretch of the North Fork of the American River in Placer County, California, was added to the national Wild & Scenic Rivers system. With its headwaters in the Granite Chief Wilderness and proposed additions, the North Fork of the American begins in the steep terrain where the granite cliffs, glaciated valleys, and meadows dominate the landscape.

The wild and scenic section, beginning near Heath Springs and running downstream just short of the Colfax-Iowa Hill Bridge includes what is popularly known as the "Giant Gap" section of the river.

In addition to designation of the river corridor, protective status was conferred to the "Gold Run Addition Area,"-- a special extension of the W&SR "corridor". Extending more than a mile north of the river, the "Addition" includes land of historic importance known as the Gold Run Diggings, a scenic and recreational interchange with access to the North Fork of the American River. The area also includes Canyon Creek, a perennial stream of significant flow that cascades over no less than ten scenic water falls as it drops 1,800 feet to the meet the river.
Congress established the Wild and Scenic River System in order to protect rivers with outstanding, remarkable, scenic, recreational, geologic, fish and wildlife, historic, and cultural values. In order to ensure that the qualities of these lands are protected, key inholdings must be acquired when they become available.

GOLD RUSH HISTORY

The North Fork American Wild and Scenic Corridor is steeped in California Gold Rush history. Close to the towns of Gold Run and Dutch Flat, on the ridge dividing the North Fork American from the Bear River were a series of hydraulic mining claims. A network of trails and old mining roads threads through the old hydraulic mine diggings, and has been used by local residents and visitors for more than a hundred years.

While gold mining on the North Fork American may have begun as early as 1848, the high gravels at Gold Run were not discovered until the spring of 1852. Evidence of the historic effort to work the deep gravels of the Eocene-age river channel is found throughout the property. Canyon Creek was itself the site of "tail sluice" claims, in which the tailings discharged from various mines were run through sluice boxes a second time. Canyon Creek was fitted with huge sluice boxes over the last two miles of its course to the North Fork American. Today, only the old trail used by sluice box tenders clings to the canyon wall.

TRAILS AND OVERLOOKS

Acquisition of key parcels will support the development of desirable trail access into the river canyon in the Gold Run-Pickering Bar-Canyon Creek vicinity.

The Paleobotanist Trail, as it is known to local hikers, winds through a region of the diggings not accessible by car or truck, where large pieces of Eocene-age petrified wood may still be found. There are also beds of clay, containing leaf impressions from extinct tree species, in this area. The Paleobotanist Trail begins in a forest of large pine trees, which, although second growth, have not been cut since the 1860s, and many trees have reached three to four feet in diameter. This forest in itself is an attractive destination for hikers. Fine views of the North Fork canyon and Giant Gap may be had from the high bluffs.

Two historic trails, both dating from before the Gold Rush descend to the North Fork American from within the Gold Run Addition. The Pickering Bar Trail heads up on BLM lands at the southern edge of the diggings. The Canyon Creek Trail begins in Potato Ravine Pass on GRP lands, passes onto BLM lands, and then re-enters GRP lands for the remainder of its course down to the North Fork. It passes many waterfalls along the way, and presents an unusually rich variety of wildflowers, ferns, and shrubs. This trail is one of the more scenic trails in the North Fork American canyon.

The Gold Run Diggings, generally, have long been enjoyed by hikers and equestrians, who have paid scant attention to where BLM lands end and private lands begin. The area presents a substantial fragment of open space in one of California's fastest-growing counties. It is contiguous to the larger tract of open space of the North Fork American canyon, and forms part of a refugium for wildlife, supporting healthy populations of deer, bear, foxes, bobcats, and even mountain lion.

PROPERTY DESCRIPTIONS

The largest parcels are located in the Gold Run Addition to the North Fork Wild and Scenic Corridor. All parcels are contiguous to BLM land holdings, are without structures, and provide linkage between federal land parcels. The public access where appropriate would provide important access to the North Fork Wild and Scenic River Canyon.

Several of the parcels include portions of an historic trail system, including the Paleobotanist Trail, the Canyon Creek Trail and the Giant Gap Trail-from Garrett Road to Lovers Leap (a popular scenic overlook on the rim of the North Fork canyon in Giant Gap).

The primary purpose for these acquisitions is to consolidate federal lands holdings in the Wild and Scenic River corridor for the North Fork of the American River, which will facilitate BLM's management effectiveness within the river corridor and enhance the overall public enjoyment of the area.

The Canyon Creek Property and Gold Run parcels. There are approximately 660 acres of land with historic trails giving access to the North Fork American Wild & Scenic River. Congress originally created the Gold Run Addition to enable public access to the North Fork American Wild & Scenic River by including the full length of the Canyon Creek Trail. In addition the rich history of the Gold Run area, the fine grove of tall pines beside Garrett Road, and the unusually fine scenery in and around the diggings support the inclusion of these parcels in the project.

Canyon Rim View shed. Acquisition of two parcels, contiguous to BLM land holdings, without structures, would gives linkage between federal land parcels. The only public access to these private lands would be by boat on the river. There are roads on the uplands, but they only access other private lands and not the offered parcels. The parcels are owned by two different landowners and are 120 and 80 acres in size.

Lovers Leap Trail Easements. The Lovers Leap Trail crosses eight different parcels. Purchase of trail easements and/or fee title would allow the BLM to complete the trail to the Lovers Leap overlook which provides unusual scenic views of the river canyon.

Green Valley area. A 55 acre parcel owned by Gold Ring Placer Mine Properties

SUMMARY

The total acreage to be acquired would be approximately 1,000 acres. Land values are estimated to be in the range of $1,500 to $3,000 per acre. The estimated purchase price for the project is $ 2,000,000 - $3,000,000.

Sawtooth Ridge Basalt Dated!
[North Fork Trails blogpost, March 26, 2005:
http://northforktrails.blogspot.com/2005/03/sawtooth-ridge-basalt-dated.html
]
Over the past few years I have occasionally gathered samples of basalt, from this area, and sent them away to Professor Brian Cousens, in Ottawa, Canada. Brian has been investigating the petrology of basalts and andesites north of Lake Tahoe, and south of Truckee. He has spent quite a lot of time in Squaw Valley, which had been a major eruptive center, in the closing phases of Tertiary volcanism.

My interest goes to geomorphology: how old is the North Fork canyon, say?

If we could answer that question, we would then guess the same age for all other major canyons in this part of the Sierra.

It is clear that all these canyons--all the forks of the Yuba and the American, in particular--are relatively young, and have been incised into a generalized volcanic mudflow plateau. The flat-topped ridges seen everywhere in middle elevations are relicts of this surface. And beneath these "young volcanics" are buried remnants of the "ancient bedrock" land surface.

In more detail, there was an "ancestral Sierra," in which a system of broad valleys had evolved over millions of years, a somewhat over-mature landscape in which streams aggraded (built up thicknesses of sediments in flood plains) rather than eroded.

We have a fine fossil flora from remnants of these old (55 m.y.) river channels, preserved on the divides between the modern canyons, as for instance at Gold Run.

The ancestral Sierran landscape was developed upon a complex of different bedrock types, from granites to serpentines to slates, with chert and limestone and more. A system of ridges ran north and south, along strike of the more resistant rocks, which were often metavolcanics called "greenstone."

About 30 m.y. ago, rhyolitic eruptions blanketed the region in volcanic ash, and some of the shallower of the existing valleys were filled outright. New patterns of drainage would then form. More volcanic ash would fall, filling these brand-new valleys.

Then, say, 15 m.y. ago, the eruptions became andesitic, and andesitic mudflows or lahars swept over the area, often filling the valleys, whereupon new drainage patterns would arise, but then new lahars would fill those new valleys.

Over millions of years, a generalized plateau of andesitic mudflow developed. Only a few parts of the Ancestral Sierra stood above the volcanic sea. Banner Mountain, beside Nevada City: and Dutch Flat's Lovers Leap, and it only by the skin of its teeth.

And then, finally, at long last, volcanic activity began to wind down. Eruptions of basalt sent streams of lava down the valleys draining high and mighty places like the Squaw Valley Eruptive Center.

Summarizing, the "standard sequence" of the Tertiary volcanics, from old to young, is

1. Valley Springs fm. (rhyolite ash, some welded tuffs).
2. Mehrten fm. (andesitic lahars etc.).
3. Basalt.

Now, most of these basalts have been eroded away entirely. In the high country they are fairly common, most notably of all at Devils Peak, made of columnar basalt.

The thing is, since they are youngest, and since basaltic lava is famously liquid and runny, these basalts ran down and partially filled valleys which almost must have preceded the incision of our modern canyons. I don't know if this is at all clear, but my thinking is, the modern canyons developed *after* the basalts. So if a patch of basalt on Sawtooth Ridge, for instance, is 5 million years old, then that too is the age of the adjacent North Fork canyon. And then we could say, "Broadly, the canyon is five million years old and two thousand five hundred feet deep, hence the average rate of incision is six inches per thousand years."

The nascent North Fork likely made quick work of the young volcanics and began incision into the ancient bedrock quite early on.

But how early? Oh, if only we could date the basalts!

And just where are these supposed basalts?

Well, it turns out that on a ca. 1900 geological map of this area, by Waldemar Lindgren of the USGS, quite a few small patches of "Pliocene basalt" are identified on ridgecrests between the modern canyons.

And among the most southerly of these little basalt patches, is one on Sawtooth Ridge, and another on Lowell Hill Ridge. I sent samples of these to Brian a couple years ago or so. He did a detailed chemcial/petrological analysis of the basalts, which varied significantly, one from the other; so it began to seem we had two very distinct and disparate lava flows on our hands, although topographically and stratigraphically, the two sites were equal.

Both sites are on ridges where no continuous volcanic plateau remnant remains, but smaller remnants persists as knolls, while the passes are commonly at the level of the ancient bedrock, on both ridges, the Shoo Fly Complex metasedimentary rocks.

Both sites show the basalt in direct contact with andesitic mudflow, but both flows sit directly on Shoo Fly basement.

It should be noted that the topgraphy has completely reversed: both flows were in the bottoms of valleys, now, they are on the crests of ridges.

OK. To make a long story short, dates have finally come in on the two samples. They are indeed disparate, as the Lowell Hill basalt came in at 16.3 m.y., while the Sawtooth basalt came in at 3.82 m.y.

Hence if the assumption is correct, that incision of the North Fork canyon began after the Sawtooth basalt, we have a nominally 2500-feet-deep canyon which is only 3.82 million years old, and now we have .654 feet/thousand years, or roundly, eight inches of incision per thousand years.

A few miles upstream, the North Fork canyon is over 3000 feet deep.

So what are we to make of the Lowell Hill basalt, at fully 16 million years? It is coeval with the andesitic mudflows, so far as I know, so it is not much of a stretch to imagine some basaltic eruptions from time to time. The age of 16.3 m.y. is indistinguishable from the age of the Lovejoy Basalt, so widely exposed farther north in the Sierra and nearby areas. It would really be a hoot if it turned out that the Lowell Hill flow is in fact the Lovejoy; but Brian seems to think that's impossible, for its chemical signature is much different than the Lovejoy's.

Clearly more samples should be gathered, from the Lowell Hill and Sawtooth sites, as well as from other potentially related flows, farther north, near Bowman Lake, etc. I sent Brian samples from Lyon Peak, Needle Peak, and another nearby flow, and also from Devils Peak, last summer. It will be exciting to hear what dates come in for these flows.



4 comments:

  1. In 1978 Russell mentions "scramble down to the keyhole". Never heard him mention it, any idea where he is writing about?
    In the 2003 entry Canyon Rim View is listed as a desired acquisition. That may be the property along the old Fords Bar Trail. Part of that property includes a nice ridge that extends out into the canyon providing great views of the canyon and river. Development on this ridge would significantly impact the view shed in the canyon.

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  2. The "keyhole"—

    that's what Russ called the roundest of the several ledges on the ridge below the Lovers Leap viewpoint. Surrounded by brush, the opening looked like a keyhole from a certain spot above. That's my recollection anyway; I tried to confirm that by searching for the term in Russ's digitized writings, and only turned up this mention, in a transcription I did from his 1977 journal, but it is not specific:

    "i never made it to neil's last night, even though i drank a small cup of coffee. it just felt too good and satisfying to lay on the couch. he may come by this morning though, and if so we'll make an attempt to reach the keyhole."

    I suspect that more about the keyhole may turn up as I continue to work through the non-digitized (non-searchable) writings this year. Greg or Neil or someone may be able to confirm the reference too.

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  3. Ron, is the property you mention on the Ford's Bar Trail ridge available for acquisition now?

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  4. I'm thinking that the keyhole might be the cave below Lovers Leap that we scrambled down to with Cindy.
    I don't know the current status of the parcels out above Fords Bar. Several years ago I heard that there were access issues with the property. I also believe that the BLM had discussions with the owner for some of the parcels on the ridge and down at the river. BLM would like these as they are in the wild & scenic corridor. The BLM also has a parcel up by Magra Rd that might be able to be used or traded for an access.

    ReplyDelete