﻿390 ME. G. BARROW ON THE [Aug. I908, 



Summary. 



The facts regarding this strange and absolutely unique deposit of 

 wolfram may be summed up as follows : — 



(1) It occurs above the 750-foot platform, and thus contains the whole of the 



materials of a very old and long-coiitiuued decomposition. 



(2) It was probably protected from being washed away during periods of 



sudden floods, by being frozen, or snow-covered. 



(3) A vein or veins occur close by, and the decomposition-products from 



these have been carried down into the adjacent hollow and thus have 

 locally enriched the unassorted wash. 



Method of working the Deposit. 



The working of this deposit is greatly facilitated by the steady 

 rise of the granite-floor or 'shelf upon which it rests. This rise 

 is sufficient, not only to prevent all chance of waterlogging by the 

 accumulation of debris in rear of the work, but also to admit of 

 the building of a series of low walls or dams with the larger 

 fragments of the debris. These walls, being built across the groove 

 or hollow from which the wolfram-deposit has already been 

 extracted, form a kind of settling-pond into which the extremely- 

 muddy water, resulting from the washing of the ' unassorted head/ 

 is directed. On reaching the wall the flow of the mud is at once 

 arrested, the coarser sand-grains are immediately deposited, and the 

 water which passes through the wall contains only the finest mud. 

 But the sand, being deposited well above the wall, itself in turn 

 acts as a still more efficient filter, so that in a short time the dirty 

 water is actually filtered by sinking through this deposit of sand 

 before reaching the wall at all, whereby complaints from riparian 

 owners lower down are largely avoided. It will be seen at once 

 that a fair slope is necessary to permit of the utilization of such a 

 device. AYhen this temporary settling-pond has been filled with 

 sand and mud to the brim, it is of no further use, and another wall 

 is built immediately above. The first settling-pond at the end of 

 the operation has become a step in the hill-side ; and, as the work 

 proceeds, a series of these steps is built up, which are clearly shown 

 in the photograph (PI. XLY) taken by Mr. Hall. 



As there is no water locally available, a good supply has been 

 obtained from the head of an adjacent small stream, being brought 

 round the end of Euttern Hill in a trench or leat ; this terminates 

 at the edge of the deposit far above the starting-point of the works, 

 and thus much labour has been saved in wheeling the dug material 

 to the washing-point. 



The water from the leat is turned into a short wood-lined trough, 

 terminating in a small waterfall with a drop of about 2 feet, a bar 

 being placed at the lip of the fall, above the water, to regulate the 

 flow. By raising or lowering this, more or less water passes 

 under. The height of the fall, too, varies somewhat with the grain 

 of the material treated ; if the ore and associated earth is fine, the 



