Show gold placers in sierra county coun ty L WRITTEN FOR THE MINING REVIEW BY G CHESTER BROWN M E F san francisco cal march 25 sierra county california in the heart of the sierra nevada mountains is bounded on the north by plumas on the south by nevada N and on the west by yuba counties and on the east by the state of nevada the surface is extremely mountainous and deeply furrowed by canyons through which flows the yuba river slate and canyon creeks and their tributaries tributa ries all of which have yielded large quantities of gold the formation consists of a heavy mineralized erali zed slate of the Jur period of the epoch which are by intrusive dikes of diorite and basales of a later period the river chan pursued with great success at first shafts were sunk to the gravel channels but the best results have been obtained by tunneling the tunnel sites are located where the lowest depression of the channel may be penetrated the cost of mining and working by this method does not exceed 1 per cubic yard the hydraulic mines are closed down to a great extent only a few working on a small scale due to the enforcement of the debris laws yet the gold output is considerable at one time 60 per cent of the production came from this region the st louis and port wine channel has a known length of sixteen miles and L 0 zy va coal Co Cl foai 0 0 0 7 aea roc eiyo S i nels are of the pliocene period and rivers of considerable size flow through the country rock disintegrated the same thus freeing the per clous metals such as gold platinum etc the gold is distributed through the gravel which has a thickness of from four to eight feet the best values being found on the top of the bed rock A period of volcanic activity took place probably during the pliocene period that covered a large part of the country with lava boi boulders liders and tuffs thus sealing up the large streams subsequently the present system of rivers was formed cutting deep narrow channels through the volcanic material and leaving the old channels exposed in the he form of ridges the course of the present streams is northeast and southwest drift mining especially where wh ere the lava cap has considerable thickness has been some of the best drift and hydraulic mines in california are on this channel the following districts were the largest producers rowland howland flat grass flat gardiners gardinere Gar diners point 10 port wine pine grove cedar grove scales st louis and chandlerville Chandl erville a total of among the modern companies may be mentioned the sierra union with linear feet on the channel and and one main working tunnel this campay has title 0 io o excellent water rights on slate creek and its tributaries tributa ries the washington blue lead covers 2600 linear feet on the channel this channel is covered to a great extent with volcanic flow and so is worked as a drift mine the estimated gold in sight is the gold valley composed of acres is both a drift and a hydraulic property this group is located on the gibsonville Gib sonville and la porte channel which has a length of fifteen miles and a production of over is claimed estimated gold that can be recovered this company obtains its water supply from canyon creek over two thirds of all the gold obtained from these channels came from a depth of not over four feet which made mining very easy for the pioneers and which led to a big production drift mining may be pursued without interruption during the entire year while hydraulic operations are limited to a period of six months the location for mining is ideal as plenty of wood and water are at hand for all purposes |