THE INFUSORIAL DEPOSITS: CLYDESDALE CLAIM. 



225 



enormous masses of this u white lava" in other hills of nearly equal height 

 in the immediate vicinity, and there are also very numerous boulders of it 

 in the gulches running down the hill above the " picture-rock " quarries. 

 What the material is which lies below the level of these openings is not 

 known ; neither has the depth to the bed-rock surface been ascertained, but 

 it is probably in the neighborhood of a hundred feet. It is very likely that 

 a considerable portion of this thickness is made up of a white lava/' and that 

 there is a small amount of gravel at the bottom. 



Another locality of a very white, fine-grained, and probably infusorial 

 material is the Clydesdale Claim, in the " Long Canon Country/' about a mile 

 from Blacksmith Flat* This claim is on the south side of Long Canon, on a 

 spur between it and Wallace Carton, a little branch coming in here from the 

 southeast. Here there have been some two or three acres washed off 

 by the hydraulic process, the general appearance of which ground is very 

 similar to that at Michigan Bluff, there being a great preponderance of 

 quartz boulders in the gravel, and some of them being very large. In the 

 western portion of the area washed off the gravel is covered by some twentj- - 

 five or thirty feet of gray, micaceous, sand " cement," precisely similar to 

 that which forms the roof of the mines at Bath and Forest Hill. Here, 

 at one point, a large detached block of snow-white material, appearing to 

 be infusorial silica, was found by Mr. Goodyear, which undoubtedly came 

 from somewhere in the volcanic ash " cement " overlying the gravel, which 

 itself was overlain by a thickness of eight or ten feet of clayey matter, 

 mixed with small fragments of the bed-rock, some of which was exceed- 

 ingly delicately and finely stratified. Over all, and forming all the higher 

 portion of the ridge, came the ordinary, bouldery, dark-colored volcanic 



U 



cement." 



At Prospect Flat, three fourths of a mile southwest of Smith's Flat, which 

 is about three miles east of Placerville, on the Carson Road, is a locality of 



i 



infusorial silica, from which material seems to have been obtained for com- 

 mercial purposes. There is a shaft on the Flat, about a hundred feet deep 

 to the bed-rock, and the whole of which is in * white lava," with the excep- 

 tion of three or four little streaks of metamorpliic gravel intercalated in the 

 mass at different depths. The locality from which the infusorial material 

 has been obtained is in the side-hill, just southwest of the Flat, and probably 



* For the locality of Blacksmith Flat, see ante, p. 98 ; consult also the diagram illustrating the region 

 covered by Mr. Goodyear's explorations. 



