218 ON THE DETRITAL TIN-ORE OF CORNWALL. 
same broad, shallow, pit.* The undisturbed portion consists of,— 
(Qe Wesetablesmouldl gees select iierel- digo ON ETDS 6 inches to 1 foot ;— 
(2). Angular and subaneular bodies of quartz, clay- f 
slate, laminated schorl-rock, elvan, and of 
various vein-stones from the slate formation, 
with—here and there, but very rarely—a few 
Stonestofmonamitebyan sieytelene cielo sire anete ere sleiohe 3 > «6 gy 4 feet ;— 
(3). The tin-grownd, which closely resembles the 
overburden ; save that it is thinly mixed with 
both rounded masses and perfect crystals of 
tin-ore, but all of exceedingly small size .. 1 foot to 2 feet ;— 
The Shelf consists of clay-slate, moderately hard and very fissile in 
some places; but in other it is merely laminated clay. 
The. hamlet of Tregoss and the tenement of Pendean occupy 
(so to speak) a peninsula, which projects, from the eastern end, 
far through the middle of the moors. Though scarcely higher 
than many heaps of rubbish left by early workmen, it bears 
neither trace of erosion nor fragment of detritus.t 
On central portions of the region operations have been, long 
since, discontinued ; but towards the southern margin—where de- 
trital deposits approach the eastern-central range of granite—a few 
workmen still glean small quantities of stream-tin-ore as long as— . 
but no longer than—the rains of winter and spring supply them 
with water. 
At Gun-deep, in Saint Dennis, a pit has been sunk through— 
if) Vegetable mould ey rereretelotersiclaielerastelelejere ogdbo0050 6 to 12 inches ;— 
A 
(2). A mixture of micaceous clay-slate, laminated schorl- 
rock, quartzose slate, quartz, elvan, and occa- 
sional stones of heals ocondagodoocnodDODS 6 4 feet ;— 
@Bjo IRMA. asooosasp0cd00a0000000000000000000000000 1 foot ;— 
(4). The tin-ground was not thought worthy of being 
wrought. 
At Gaverigan—a south-western part of Tregoss moors—near the 
confines of: Saint Dennis and Saint Columb-major,{ a mixture of 
angular, subangular, and rough spheroidal masses of various rocks 
* Now (1873) wrought by William Tellum and John Moss. 
+ ‘‘ Several patches on these moors are, indeed, enclosed, and brought 
into tillage; such parts, however, are higher than the general surface of the 
moor, to which circumstance their superior fertility may be owing, the more 
elevated ground having been exempted from the diluvium that covers the 
lower levels.” Boasr, Cornwall Geol: Trans: iv, p. 248. 
} Rashleigh, British Minerals, i, p. 3; Pl. i, Fig. 3. 
