QA4 ON THE DETRITAL TIN-ORE OF CORNWALL. 
tions consist of much the same ingredients as both the adjoining 
and the neighbouring rocks and vein-stones.* They commonly 
occur in the state of sand and gravel ;—differ little, if at all, from 
the beds of brooks in their vicinity ;—and are disposed in, almost 
countless, thin layers, which alternate with yet thinner partings 
of hardened clay. 
(VI). Tin-ore (Suoves+) sprinkled on the surface at various alti- 
tudes. The valleys and low-grounds—although, by far, the largest 
and richest—are not the only repositories of detrital tin-ore ; for 
-_  #* Henwood, Cornwall Geol: Trans: iv, pp. 60—64. Ante, pp. 195, 
196, 200, 213, 214, 215, 217, 218, 230, 231. 
+ “Title stones, lye both in and nere the Brookes, and vpon the 
‘‘mountaynes wher the metall lyeth; theis stones they call the Shoade, 
‘being parcel of the veyne of owre, which being dismembred from the bodye 
‘‘of the Loade, are meanes to direct to the place of profite, as the smoake 
‘“directeth where the fire lurketh.” Norprn, Speculi Britannic, p. 12. 
“To find the Loadworkes the first labour is employed in seeking.... 
‘“‘ certaine Tynne-stones, lying on the face of the ground, which are termed 
“ Shoade, as shed from the main Loade, and made somewhat smooth and 
“‘yound, by the waters washing and wearing....Having found any such, 
‘“‘they coniecture by the sight of the ground which way the floude came that 
‘‘brought them thither, and so give a gesse at the place whence they were 
‘broken off.” Carzw, Survey of Cornwall, (H. P.), f. 8. 
“The shouders...pretend to such a nicety, as by the roughness or 
‘smoothness of the shoad to tell you how far off the main load lies; nay, 
‘to fit the very shoad, allowing for the wearing of it, to the place of the load 
“that it was broken off from by the flood.” Canrnw, Survey of Cornwall, 
(Tonkin’s Notes to Lord De Dunstanville’s Edition), p. 29. 
“Tin is [sometimes] found disseminated on the sides of hills, in single 
“stones, which we call Shodes, sometimes a furlong or more distant. from 
“their lodes, and sometimes these loose stones are found together in great 
‘numbers, making one continued course.” Boruase, Natural History, p. 161. 
‘“‘ Shode [tin-ore] is disjunct and scattered, to some declined distance 
‘‘from its parent lode, and is pebbly or smoothy angular.” Prycn, Miner- 
alogia Cornubiensis, p. 67. 
‘“‘Shoad-stones are partially rounded and apparently water-worn ; 
“they are found on, or at very small distances below, the surface; their 
‘‘ mineral characters are much the same as those of neighbouring lodes, of 
‘“‘which, indeed, it is supposed they were originally portions, removed by 
‘“‘ diluvial action. As shode stones usually contain tin-ore they have been 
‘‘ carefully culled, and few now remain in the mining districts of Cornwall. 
“The Shoder commonly commenced his labours in low-grounds, where tin- 
‘‘ bearing diluvium abounded, and carefully sought tinny shode-stones as he 
_ “ascended the neighbouring hills ; as he advanced he found them in greater 
‘“numbers, and at length he traced them to, what he believed to be, the 
‘“‘ parent lode.” HeEnwoon, Quarterly Mining Review, i, (1830), p. 403. 
