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CHAEACTEK OF THE GEAVEL : PLACER COUNTY 



95 



wanting. But even here the soft bed-rock is said to be rich and to have paid, over much of the 

 area thus situated, almost as well as where there was gravel. There are still to be seen rich 

 streaks in the gravel, "lousy with gold" to use the miners' phrase. The Back Channel* is be- 

 lieved to be rich, having been sufficiently prospected to prove this. The gravel appears to be 

 deepest in the deeper portions of the channel ; but it is not deep enough to cover the high bed- 

 rock, nor does its upper surface lie level ; but, to a considerable extent, it conforms to that of the 

 bed-rock itself, especially in the larger channels. Numerous quartz boulders have been found hero 

 rich in gold, and some of them were remarkable. Eor instance, it is stated that one boulder 

 weighing only twenty-nine pounds contained $3,700 in gold, which metal made up more than one 

 third of its weight. 



In the region lying between the heads of the three canons, known as First, Second, and Third 

 Brushy, directly north of Forest Hill, and from one to three miles distant from that place, there is 

 a large amount of gravel. Some of this is uncovered ; other portions have a deep covering of vol- 

 canic material. The gravel varies much in thickness, ranging from a few feet to as much, perhaps, 

 as three hundred. A peculiar feature of this region is, the great depth to which much of the vol- 

 canic conglomerate has been decomposed. This decomposition has developed in a remarkable 

 degree the concentric structure of the volcanic boulders. These are banks in which, almost with- 

 out exception, every boulder-will exhibit this structure, with sometimes a hard kernel in the centre, 

 and sometimes without one. Another feature of this district is, the frequency of streaks or beds 

 of auriferous gravel overlying the volcanic cement. Distinct channels can with difficulty be traced, 

 in the region in question, on account of the wide diffusion of the gravel, the deep covering of vol- 

 canic material with which it is overlain, and the very limited extent to which the bed-rock itself 

 has been exposed to view. 



At Smith's Point, between First and Second Brushy canons, in the banks exposed by the 

 hydraulic operations, the gravel ranges from fifty to sixty feet in thickness. It is made up of peb- 

 bles and boulders of metamorphic rock chiefly, with some of quartz ; they are generally under 

 twenty-five pounds in weight. The gravel is in places more or less interst ratified with beds and 

 streaks of sand, which arc not continuous for any great distance, and which are not exactly hori- 

 zontal, but slightly inclined in various directions. Above the gravel lie alternating beds of ash, 

 more or less clayey, and volcanic conglomerate, occasionally containing very large boulders. Far- 

 ther back on the crest of the ridge the regular volcanic conglomerate occurs in heavy masses. 



x\t Yankee Jim's the gravel is composed of all sorts of metamorphic rocks, and few boulders 

 are met with which aro too lartre to wash through the sluices with a good head of water. The 



proportion of quartz is small. Over the central axis of the Big Channel the gravel averaged, for 

 most of the distance, over a hundred feet in thickness ; and the average over the whole ground 

 washed was, probably, forty feet. Over almost the whole of this ground the gravel was uncovered ; 

 but at the east end it is overlain by the volcanic cement, which hero also shuts out a considerable 

 portion of the thickness of the gravel. 



At Georgia Hill on the south side of the Devil's Canon, a little below Yankee Jim's, an area has 

 been washed off GOO or 700 feet long by an average of 100 wide ; in the western half of this 

 ground the gravel was uncovered and reached a depth of 100 feet or more, but the eastern half 

 was covered with volcanic cement which in going easterly from the middle of the ground worked 

 gradually descends, and nearly shuts out the gravel. 



At the Oro and Dardanelles claims, near Todd's Valley, the lower portions of the banks consist 

 of blue gravel. Above this in the Oro and the eastern part of the Dardanelles is red gravel to the 

 top ; but in the central and southwestern portion of the last-mentioned claim the upper heavy 

 bank of red gravel is overlain by a mass of volcanic cement, whose maximum thickness, so far as 

 it is exposed, is not far from 100 feet. The gravel is generally very hard ; and the banks, even 

 where they have not been touched for five years, are usually very smooth, and often very nearly 



* See page 106 for a description of the so-called Back Channel. 



