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THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 



surface of the bed-rock ; "but there their axes are nearly parallel with the strike of the slates, or 

 K 10° — 15° W., and their direction points exactly to Georgia Hill, on the south or opposite side 

 of the Devil's Canon. It appears, therefore, that there were two channels on the bed-rock here, 

 the first or largest one coining from the east, and the second coining from the southeast, the two 

 forming a junction at or near the head of Yankee Jim's Canon, which now heads just between 

 the two channels. The true pot-holes in the rock were generally barren. In the upper or eastern 

 portion of the Big Channel the richest pay was on the bed-rock ; but toward the lower end the 

 surface of the bed-rock was not so rich, and the upper gravel paid much better. 



At the Dardanelles and Oro claims, near Todd's Valley, the surface of the bed-rock is exceed- 

 ingly rough and irregular, being filled with depressions of various shapes, some of which are from 

 fifteen to twenty feet deep. The whole surface of the high as well as of the low bed-rock is well 

 water-worn. Numerous small, elongated furrows are worn in the surface of the rock, which vary 

 from a few inches to one or two feet in depth, and often several feet in length. These furrows 

 run across the edges of the strata, and are nearly parallel with each other ; their direction is about 

 S. 65° W., indicating that the water on the bed-rock flowed southwesterly. 



In the Spring Tunnel, near Volcanoville, the bed-rock is said to have been found very uneven, 

 so that the tunnel, which starts 150 feet below the rim-rock, and was driven for 900 feet in a 

 direction a little west of north, passed several times alternately through bed-rock and gravel. 



At a point about a quarter of a mile east of the Franklin Claim on the south side of Little Span 

 ish Hill near Placerville the furrowings of the surface of the bed-rock are unmistakable, and run 

 in a direction about S. 46° W. magnetic across the edges of the slates which strike N. 44° W. 

 magnetic and stand nearly vertical. 



3. Crevices in the Bed- Rock. 



In the Morning Star Claim, near Iowa Hill, a crevice was struck in the tunnel, which is said to 

 have been 150 feet in length at the top and about eighty at the bottom, and from one to ten feet 



■ 



wide. Its direction was parallel with that of the strike of the slates, and it was filled with gravel 

 mixed with fragments of the bed-rock. This crevice is said to have yielded $ 40,000. 



At El Dorado Hill, near Michigan Bluff, there is in the outer portion of the hill a deep gulch 

 in the bed-rock running nearly north magnetic and descending with a very rapid grade toward the 

 north for some four or five hundred feet and then ending by abutting sharply against a high mass 

 of bed-rock. This gulch is said to have been extremely rich. It is fifteen to twenty feet deep 



below its rims. 



In the western portion of the Hook and Ladder Claim, near Placerville, there are three or four 

 crevices in the bed-rock, running parallel with the stratification, and which arc filled with gravel 

 and little broken fragments of the slate. They have been very rich in gold, far richer than any 

 of the gravel on the surface of the bed-rock. Not one of these crevices has yet been worked to 

 the bottom, and their depth is therefore unknown. They extend into the adjacent location, — the 

 Llacklock. 



* 



Near Aqueduct City there are narrow crevices in the decomposed slates, occupied by gravel, 

 which seems to form vertical dykes as it were. These run down to depths of from twenty to a 

 hundred feet. These gravel-filled crevices seem to have been once occupied by limestone, and 

 this has been removed by the solvent action of water, leaving a cavity into which the gravel has 

 later been washed. 



4. Character of the Gravel Deposits. 



At Wiessler's Claim, Towa Hill, over a considerable portion of the area worked, especially towards 

 the southwest, the gravel resting directly on the bed-rock varies from two to ten or more feet in 

 thickness, and is overlain by a stratum of sand, containing much mica, and called "pipe-clay"; 

 this ranges from ten to fifteen feet in thickness. Over this again is gravel to the top of the bank, 

 with only thin layers of sand irregularly intercalated in it. Elsewhere there is no sand, but only 



