VICINITY OF OROVILLE AND CHEROKEE FLAT. 



485 



"\ 



is small, the slide advances about as rapidly as the face of the bank is removed, and no progress is 

 made towards getting at the pay gravel, which is supposed to lie next the bed-rock. The water 

 used is brought from the west branch of the Feather River. The ditches, flumes, pipes, and natural 

 water-courses, through which the water has to pass before reaching the mine, amount to fifty miles 

 in length. Two grades of gold are found in this ravine, — one fine, scaly, and floury ; the other, 

 coarse and nuggetty. I have no data in regard to yield or expenses. 



The ridge dividing Morris Ravine from the upper portion of Schermer's Ravine is so low that at 

 first sight the two ravines appear to belong together. In Schermer's Ravine no bed-rock is to be 

 seen. The ravine is supposed to be filled with the same kind of material as that which gives 

 Morris Ravine its value, though it has never been so rich, and no profitable mining has been car- 

 ried on there. 



On the crest of the saddle between Table Mountain and South Table Mountain, at the head of 

 one of the branches of Schermer's Ravine, I made the altitude of the base of the basalt to be 900 

 feet. At this point there was a stratum of a peculiar sand-rock underlying the basalt and resting 

 upon a mass of gravel. It seems to be an imperfectly compacted mass, made up of grains of vol- 

 canic rock. On the western slope of this saddle, and about 250 feet below the crest, tunnels have 

 been driven into the gravel just mentioned. One of the tunnels has readied a length of 250 feet. 

 The gravel is coarse, pebbles from six to eight inches in diameter being common. There is almost 

 no quartz to be seen in the tunnel ; the pebbles are of easily decomposable varieties of metamor- 

 phic rock. Gold was not found in paying quantity. In this gravel supposed remains of 

 organic life have been found, but the specimens that I saw wore not well enough preserved to be 



identified. 



In Coal Canon, on the western side of Table Mountain and between two and three miles south 

 of Cherokee Flat, the basalt and the underlying strata have been eroded in such a way as to leave 

 a good exposure, a few feet in thickness, of the upper portion of the material on which the basaltic 

 cap rests. The altitude of the base of the lava at this point I made to be 1,049 feet. The thick- 

 ness of the lava is about 150 feet. The width of the "cave," as it is called, I estimated at 300 



* 



feet, and its depth, under the overhanging cliff, at 100. The bluffs of basalt are nearly vertical, 

 and show very well indeed the prismatic columnar structure so common in that rock. In the 

 canon there are huge piles of basaltic debris, much of which looks as fresh as if it had only recently 

 fallen. See section (Plate X, Fig. 3). The strata, marked with Roman numerals on the section, 

 are as follows : — 



i. Basalt. 



ii. Dark gray, sandy clay, two feet in thickness. 

 in. Light gray, sandy clay, eight to ten feet in thickness, the lower half having a yellowish 



tint. 

 iv. Rolled volcanic (basaltic) gravel, with an occasional quartz pebble, fifteen to twenty feet 

 in thickness. Quartz pebbles are very scarce ; the basaltic pebbles are nearly uniform 

 in size, ranging from three to six inches in diameter. 

 v. Light-colored, sandy clay, very compact, and very much resembling a sandstone. The 

 thickness of this stratum down to the pile of debris is twelve feet. In it a shaft has 

 been sunk to an estimated depth of thirty or forty feet. The material in the dump 

 seems to be all of the same kind. There is said to be another shaft, lower down the 

 canon, which has been sunk to quartz gravel, but my information is not positive on this 



point. 

 At the base of the lava in Morris Ravine, where I made the altitude to be 1,084 feet, basaltic 



pebbles, similar in character to those from stratum iv above, were found. No specimens were 



brought away. 



From the preceding descriptions it will be seen that the eastern edge of the Table Mountain 

 basalt probably rests for the whole length of the mountain, with the exception of a short distance 

 at Cherokee Flat, upon the bed-rock, or with only a thin layer of gravel intervening ; that the bed- 



