Collection: Books and Periodicals

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Title: The Tertiary Gravels of the Sierra Nevada of California by Waldemar Lindgren (1911) Collection Type: Books and Periodicals Source(s): Google Books # of Pages: 301 Download PDF: User Login Required Download OCR Text: User Login Required

Date Scanned: 2024-07-14 06:26:22 Item Sourced From: PDF First Created: 2025-03-17 05:53:20 Last Updated: 2025-03-17 05:53:20

Original Held At: Searls Historical Library Location: 161 Nevada City Hwy, Nevada City, CA 95959

Page: of 301  

HONEY LAKE QUADRANGLE. 115 Tertiary gravels have been mined about the head of Lights Creek, Mountain Meadows, and Moonlight for over 20 years, and their total yield is believed to be about $500,000. A little placer mining has been done on Gold Run, a few miles south of Susanville. This is the most northerly place in the Sierra Nevada at which gold mining is carried on. In 1909 the placer production of the Honey Lake quadrangle scarcely reached $5,000. Most of it came from Seneca and Crescent mills. . THE TERTIARY TOPOGRAPHY. In the bulletin mentioned Diller has shown that the drainage of this region during the Tertiary period flowed to the north and that the important river which Turner traced through the Downieville quadrangle east of the Tertiary crest of the Sierra Buttes and Grizzly Ridges continued northward until, between Mountain Meadows and Susanville, its deposits widened into large gravel areas marking the entrance of the stream into a wider valley or plain. Diller has named this watercourse Jura River, an appropriate designation which will be adopted in this description. In the Downieville quadrangle, north of the. Mohawk fault, this river flowed in a broad and deep valley, whose sides rose 1,500 to 2,000 feet above the channel. The same characteristics are maintained in the southern part of the Honey Lake quadrangle. Above the Taylor diggings, in the high gap east of Indian Valley, Mount Jura rises 1,000 feet above the -bedrock in less than a mile and the eastern bedrock ridges rapidly attain a similar height. The level bottom of Indian Valley is now under the combined influence of subsidence and erosion, 2,000 feet below the bedrock of the ancient channel. Few data are available to determine the precise character of the Tertiary surface west of Indian Valley. From the Mount Jura gap the continuation of the ancient river is clearly indicated toward the gap separating Mountain Meadows from the drainage of Indian Valley; this is occupied by a heavy body of gravels which on the northwest side descend to the level of Mountain Meadows. On both sides of this gap the bedrock ridges rise to a height of about 1,000 feet. This place marks the end of Jura River, at least so far as definite exposures are concerned. The river undoubtedly followed the present Mountain Meadows for a few miles to the northwest; the depression of the old channel is clearly marked, even if the slope of its west side has been accentuated by later faulting. To the northwest of the valley Tertiary lavas cover the whole country. Diller believes that the river here emerged from its course in the mountains into more open country and holds that the great masses of well-washed gravels of Tertiary age which underlie the andesite between Susanville and Mountain Meadows were parts of the delta deposits of Jura River. The bulk of these gravels contain no late volcanic rocks and they carry but little gold. These heavy masses of gravel continue to the southwest for about 12 miles, almost to the crest of the range and up to elevations of 7,000 feet, but the upper parts, to a great extent, consist of intervolcanic beds of Tertiary igneous pebbles. The faulting along the Honey Lake line has clearly affected their position with reference to Jura River, the channel of which lies at an elevation of only about 6,000 feet. It is suggested that in late Tertiary time, when the old outlet by way of Mountain Meadows was clogged, Jura River was forced to turn northward from Jura Gap toward Lights Canyon and Moonlight. The opinion of Diller that the high gravels southwest of Susanville have been bent over the north end of the Honey Lake escarpment has already been mentioned. About 74 miles southwest of Susanville, near the head of Willard Creek, he found a number of plant remains, which are considered by Knowlton to indicate a late Eocene age and which, therefore, are the oldest flora known from the auriferous gravels. The other fossil leaves found in this vicinity—for instance, those near Moonlight and between Susanville and Mountain Meadows—are clearly of Miocene age. Near the divide these gravels rest on a markedly uneven surface, the irregularities of which can not be attributed wholly to deformation and faulting. At Diamond Mountain the contact of volcanic gravel and granite lies at an elevation of 7,000 feet, while a few miles farther northeast, along the Susanville and Taylorsville road, the same contact has an elevation of only 5,500 feet. :