THE GRAVEL DEPOSITS: BETWEEN THE YUBAS. 



199 



With the above rapid sketch of the facilities for procuring water on the 

 divide between the Middle and South Yuba rivers, we may proceed to a 

 statement of some facts in regard to the gravel deposits. 



A reference to the map will show that there is a continuous capping of 

 lava on the ridge from Eureka down as far, nearly, as North Columbia. Be- 

 low here is only one isolated patch, at Montezuma, about a mile and a half 

 long and pointing directly toward the isolated lava-capped hills mentioned 

 as lying near the Key-Stone saw-mill. Of the thickness and character of the 

 volcanic capping the writer knows almost nothing. Neither are there any 

 dctads of altitude for this region, the elaborate series of barometrical obser- 

 vations of the Geological Survey, of which the tabulated results are given in 

 the Appendix, having been discontinued on reaching the South Yuba. In 

 general terms, however, it may be stated that the summit of the ridge, at its 

 lower extremity near French Corral, is a little over 1,000 feet above the 

 surface of the water in the Yuba; also that the height of the flat portion of 

 the ridge, above the river valleys north and south, increases gradually as we 

 go up the divide ; but that the depth of the canons in this region is not so 

 great as it is farther south among the branches of the American Kiver, or 

 farther north in Sierra County. Still, there is ample room for tailings in the 

 various steep ravines which furrow the sides of the central high divide, whose 

 table-like top rises on the whole with rapid and regular grade towards the 

 granitic High Sierra region, where lie the various reservoirs which have been 

 mentioned, and which appear to be at an elevation of about 6,000 feet. 



J- here is on this ridge, and especially towards its lower portion, a large 

 * rea °* gravel uncovered by any volcanic capping, of very remarkable thick- 

 ? and most of it not so compacted together that it cannot be moved 

 } y the hydraulic jet. It is also apparently auriferous throughout, so that with 

 < l rge supply of water available, as already described, this portion of the State 

 ers a most favorable combination of conditions for the development of the 

 yuraulic mining industry on a grand scale. A brief account of the opera- 

 lOUS 8 0ln g on in this region will be given here ; but with the expectation 



ness 





ot a fuller one will follow in a supplementary chapter or appendix to this 

 v °lume. 



go general position of the uncovered gravels in the region between the 

 1 anc * Middle Yuba rivers will be seen on the map, as well as the names 



' ( mg to the amount utilized. This includes repairs and all expenses, but not interest on the cost of 

 property and improvements. The selling price varies from sixteen to thirty cents per 24-hour incl), 

 according to the locality where delivered. 



