THE GRAVEL: EL DORADO COUNTY. 99 
ville, more than nine tenths of the whole mass of the gravel is of volcanic origin, and all the peb- 
bles are very smoothly rounded. 
At the Webber Claim, about a thousand feet east of the Excelsior, and on the south side of 
Coon Hollow Ridge, where an acre or more has been washed off, the bank is a little over a hun- 
dred feet in height. The upper twenty-five or thirty feet are of the so-called “black lava,” and 
beneath are sixty or seventy feet of smoothly rounded “mountain gravel.” The metamorphic 
gravel lies on the bed-rock, and varies from two or three to twenty feet in thickness, according to 
the inequalities of the surface of the bed-rock. The mountain gravel is said to contain gold enough 
to pay all expenses of wages and water. At Webber Hill the maximum thickness of the gravel is 
forty or fifty feet. It is overlain by white lava, which, in the eastern part of the hill, is from 
seventy-five to one hundred feet thick, and shows a decided tendency to assume columnar forms. 
Above this is “ mountain gravel,” forming the crest of Webber Hill. 
At the Confidence Mine, 300 or 400 feet north of the flume at the head of Cedar Ravine, the 
slope goes down with an inclination of five feet in twelve and is 300 feet long to the bed-rock. 
On the bed-rock is a stratum of gravel from five to eight feet in thickness, overlain by the ‘‘ white 
lava,” which extends all the way to the surface. In Cedar Ravine, near Dickerhoff’s Mill, the 
white lava shows something of a tendency to a columnar or prismatic structure. 
At Dickerhoff’s Mine in Cedar Hill the pay-gravel in the channel on the bed-rock is from three 
to four feet in thickness, and is made up almost entirely of pebbles of metamorphic rock, with 
much quartz, a good deal of which is but little rounded ; it is immediately overlain by a body of 
exceedingly fine-grained, compact material, called by the miners “ lava,” and which, in fact, appears 
to be of volcanic origin. It is believed to be of great thickness, perhaps from 100 to 200 teet, and 
it is capped by the “ black lava,” which is also fully a hundred feet in thickness, in all probability. 
Just east of Dickerhoff’s Mill in the north side of Cedar Hill, the hydraulic banks are from 
fifty to sixty feet high, the lower few feet only being a true gravel, and all the upper part of the 
banks consisting of sands and clays. In the hill immediately back of the banks these finer sedi- 
ments are also overlain first by eight or ten feet of ‘ white lava,” then by a body of “mountain 
gravel,” and finally the latter is capped with a mass of “ black lava.” 
At the Hook and Ladder Claim in Big Spanish Hill, about one mile nearly east of Placerville, 
the gravel on the bed-rock averages from four to six feet in depth, and is covered by from fifteen 
to twenty-five feet of sand, above which come heavy beds of still finer sediment, containing occa- 
~ sional thin streaks of fine gravel ; and over all a few feet of volcanic cement, the whole height of 
the bank being about a hundred feet. 
On the north side of Little Spanish Hill, about the head of Spanish Ravine, the gravel has a 
total thickness of sixty to seventy feet. At the height of twenty-five or thirty feet above the bed- 
rock it is traversed by a stratum of mottled white and rose-colored “ pipe-clay” six or eight feet 
thick. Below this “ pipe-clay ” is a mass of fine sand with some clay but no pebbles. But above 
it is pebbly gravel, which shades off again at the top into fine sand and clay, immediately beneath 
the final capping of “black lava.” 
The section of the bank, at this point, is as follows :— 
Feet. 
Volcanic breccia . : ; . : : : : : : 10-12 
Very fine sand, irregularly feed : : - : , : . : 4-6 
Streak of white pipe-clay . ; ; : aes a ara ey : 0-1 
Fine gray gravel and sand : - : 5 ; : : : 8-10 
“ Pipe-clay,” pinkish and rather had : é é ; : ; = - 8-12 
Sand, reddish below and bluish at top. : 5 er emule 15 — 20 
Gravel, rather fine, with some sand. : : ; . 3 : . 10-15 
Total height of bank : - ; : ern : : : : 75 to 80 feet. 
There are places in Little Spanish Hill, where the volcanic capping is seventy-five feet thick. 
The order of superposition of the different materials in the banks above the bed-rock, in Hang- 
