﻿Vol. 64.] HIGH-LEVEL PLATFOEMS OF BODMIN MOOE. 389 



mineral that he had hidden, disclosed the hiding-place. This led 

 to the reopening of the works at the point at which they had 

 formerly been abandoned, but now search was made for the very 

 mineral that had led to their stoppage. 



Nature of the Deposit. (Fig. 1, p. 388.) 



The wolfram-bearing deposit has been traced from the edge of 

 the marsh, where it is part of the alluvial deposits, to a considerable 

 distance up the hill-slope, where it forms part of the local * head ' 

 or 'unassorted wash,' lying in a shallow hollow or broad groove 

 pointing straight up the hill. The deposit is about 6 feet thick 

 in the centre of the hollow, thinning away towards the margins, 

 but with no appreciable diminution in the size of the constituents. 

 The latter consist of small irregular fragments of granite and vein- 

 quartz, associated with a considerable amount of finer material and 

 many bigger fragments, some of which are a foot long. There is 

 no sign of rounding in the fragments, nor of any bedding in the 

 deposit, which is a perfect example of ' unassorted wash.' Through 

 this the wolfram is disseminated in fairly-large pieces, one having 

 been found, attached to some vein-quartz, as big as the top of a 

 man's head/ Work has been carried on here for some time, and 

 has proved continuously renumerative. 



Above the unassorted wash is the usual cover of very fine recent 

 wash, that everywhere rests upon the coarser material where these 

 deposits are undisturbed ; it varies in thickness here from 1 to 2 

 feet. Close to the foot of the hill the peat comes on, at first split 

 up by seams of the finer material, but becoming solid at the edge 

 of the marsh, which it once entirely covered. Eesting directly 

 upon the old wash are a number of isolated blocks of granite, often 

 of considerable size ; these are older than the finer deposit by 

 which they are surrounded, although owing to their size they 

 project above the surface and thus appear at first newer. These 

 blocks are believed to have slid down frozen slopes, and as there 

 seemed to be few signs of denting of the surface of the underlying 

 wash, it seems reasonable to suppose that the latter was frozen ; it 

 is to this freezing that its escape from being denuded and swept 

 into the marsh below is almost certainly due. 



Local Enrichment of the Wash. 



From what has been said before, we should expect some vein or 

 veins to occur close by, to account for the enrichment of this local 

 wash ; and this has proved to be the case, the small pits of the old 

 workers being still clearly visible. They are scattered, and suggest 

 that, as in the adjacent wash, no tin, but wolfram alone was 

 present — a most unusual phenomenon. 



1 Presented by Mr. Harwood, one of the partners, to the Museum of 

 Practical Geology in Jermyn Street, London. 



