214 ON THE DETRITAL TIN-ORE OF CORNWALL. 
Levrean, in the same parish, now displays ;— 
(1). Granitic sand and GVA VCO mareyaiseeterelote ronnie ete tele ciouerel lsiere le 1 foot ;— 
(2). Peat (fen); often mixed with, and sometimes divided by 
exceedingly thin layers of, granitie sand...... 500000 1 
(3). Gyranitic matter (the Upper tin-ground) ; small sub- 
angular masses of felspar, quartz and white mica, 
mixed largely with schorlaceous matter, with parti- 
cles and granules of tin-ore in smaller proportions, 
and, in rare instances, with minute specks of gold.. 3to 6 toate — 
(4). Angular and subangular masses of granite imbedded 
in granitic sand; altogether destitute of tin-ore 
(GHGS ARAVE)) Bool 6b bode 0rs5505 choo dbo BeOS CoHe oo Ib op IS) oath 
(5). The tin-ground, comprehending angular and subangular 
bodies of granite. felspar, quartz, schorl, and various 
vein-stones, mixed with granitic gravel and sand, as 
well as with grains and particles of oxide of tin; and, 
still less frequently, with flakes of schistose matter 
and specks of gold ........eeceeeccceesceeeceees 10 to 15 feet ;— 
A few ancient shovels—some made wholly of wood, others bound at the 
edges with ironj—have been found, from time to time, in distant parts of 
this bed. 
The (Shelf) granite beneath is of ordinary texture, unequal hardness, 
and, generally of reddish hue; its surface is remarkably uneven, and the 
depressions in it are often the richest repositories of tin-ore. 
At Pit-moor, also in Saint Austell, the successive deposits con- 
sist of ;— 
(1). Vegetable mould ..........eeeeceeeerees cielolfolevelateytere 1 foot ;— 
(2). Granitic sand and gravel, in many separate layers, but 
All] hi Iblis) GIMEWEXCHE? Gancioacoadcdoe6 odcc0onSuC --.. 2to 38 feet;— 
(3). mixed with subangular masses 
of granite and of SCHOEN OC ears cteleleNefoiel-siatoleiolersteistehts Bae 
(4). The tin-ground, made up of angular, subangular, and 
rounded masses of granite, quartz, schorl-rock, and 
schorl, with similar bodies of various vein-stones and 
small quantities of tin-ore, of different sizes, but mostly 
very small. Laminez of clay-slate are sometimes, 
but very rarely, mixed with the other ingredients ....3 to 10 feet ;— 
The granitic matter (Shelf) beneath, is of ordinary texture, but usually 
it is very soft, so soft, indeed, that portions of it—on being laid open—flow 
forth in a semi-liquid state. 
* Henwood, Cornwall Geol: Trans: iv, p. 62. 
+ The workmen use ‘‘a broad Shouell, the viter part of yron, the middle 
‘of Timber, into which the staffe is slopewise fastned.” CarEw, Survey of 
Cornwall, i. 10. 
