THE PLACERS OF CALIFORNIA

Grey River Argus, Volume X, Issue 836, 1 April 1871, Page 2

THE PLACERS OF CALIFORNIA.

[weekly bulletin, ] There are comparatively few people even in California, and certainly very few abroad, who properly appreciate the enormous auriferous wealth of this State. The grand depositories of gold have as yet hardly been touched. To say nothing of the quartz, scattered so plentifully all along our great mountain ranges, and which will be worked with increasing results for generations to come, the placers of California have as yet yielded up but an inconsiderable part of the treasures they contain. It is true that the shallow placers— those made by existing streams, in what, geologically speaking may be called modern times — are nearly exhausted, though some placer mining is still going on, and there are rich surface deposits, as in El Dorado county, which only wait the introduction p,F water tp recall on a limited scale the mining scenes of our early years. But the great deep, or ancient placers of California have as yet hardly begun to be worked. These are the great storehouses of the precious metal. The yold found in the banks and bars of the tributaries of the Sacramento did come not directly from the quartz, but from these great placers, the formation of streams which ceased to run when the Coast Range was lifted from the sea. Here and there the new

water courses cut the old channels and washed down the gold to enrich the modern placers, on which California mining first commenced. But the gold thus freed was but a small portion of the xiches of these ancient deposits. The extent of these deep placers cannot be definitely ascertained until the completion of the geological survey, but we know they cover a great portion of the country along the Sierra, between ' the Feather and South Fork of the American, a tract 100 miles long by 40 in breadth, embracing parts of Plumas, Butte, Sierra, Yuba, Nevada, Placer and M Dorado,^ and drained by the Feather, the North, Middle and South Yuba, and the North and South Forks of the American. How much of this tract of four thousand square miles is auriferous, it is difficult to determine. Professor Silliman estimated the auriferous ground between the fiddle and South Yuba rivers alone, at two .hundred square miles, but his estimates were doubtless exaggerated. Mr W. "A. Skidmore, who has made an elaborate report on the placer districts of California for the United States Mining Commissioners, and who is evidently cautious in all his statements, says that if compelled to hazard an estimate of the area of the deep placers, he would place it at between 400 and 500 square miles, and would feel confident that he had rather under-stated than overestimated.- A good part of these deposits has been covered by the lava .flow from the now long extinct craters of the Sierra, and must be worked by means of tunnels ; but hundreds ef square miles lie exposed, and can be washed off whenever outlet can be secured. The depth of the deposit varies- from over 300 ft, as at Gold Run, to the depth of a few feet, as it is lost at the foothills which sink into the Sacramento Valley. At Smartsville, the depth is 240 f t; at Manzanita. Hill, '176 ft*; at North Bloomfield, 180 ft ; at French Corral, 150 f t; while in the Great Blue Lead it varies from 100 ft to 300 ft ., Mr Skidmore estimates the average depth at 120 ft, an estimate in all probability as nearly correct as any that can now be ma de. When the hydraulic dirt or gravel is washed away, a hard white or reddish cement is found beneath, composed of pebbles and boulders of quartz and metamorphic rock, dirt and sand so firmly com* posted as to be impervious to the small streams formerly used ; though with the immense streams now thrown it can be easily washed away. Underneath this white cement comes in the ancient channel the 'blue cement, which requires blasting and crushing, but which is in places fabulously rich. , :. , L - • The amount of gold held by these four or five hundred square miles of ancient placers is simply incalculable, and the most moderate estimate will go far into the billions. The ground of the American Company at Manzanita Hill, probably a fair sample, has yeilded between fifty and sixty thousand dollars an acre. The twelve hundred acres of the North Bloomfield Company, to work which on a gigantic scale, preparations are now being made, have been shown to contain, on a moderate calculation, over 69,000,000 dollars. While M. Laur, a French mining engineer, some years ago reported .to his government that the ridge between the Middle and South Yuba alone was capable of yielding 12,000,000 dollars annually for over five centuries. But without' going into calculations which seem like visionary speculations,- it is certain that ; these ancient placers contain infinitely more of the precious metal than California gave to the world from her now exhausted shallow placers, and -that how great the annual yield shall be only depends upon the increase of capital and the improvement of mining appliances. ■,"■>. a.