OF CORNWALL. ?1 
only obferve, that if thefe veins of the deatites were dug deeper, 
and fearched more effectually, the dony forts might be found in 
larger maffes, and not fo fhattery as they are now, (and mod other 
ftones indeed are near the furface) if fo, they would make very 
pretty vafes, &c. at a fmall expence: in particular, N°. V. would make 
a fine fubftance for fmall bufts and heads ; and the green done, 
N . V II, might yield a kind of forpentine marble at a proper depth, 
it being in fome parts of the cliff exceeding hard, and not near of 
fo firm a confidence any where above, as it is fome fathoms lower 
down in the vein \ 
That this, as well as other clays, is Freaked and variegated, is 
owing to the mixture and infinuation of differently coloured, moi- 
ftened and diffolved portions of earth. Hence the various colours 
of veined marble, colours inferted, during the liquefcent date of 
marbles, by the concourfe of differently fhaded earths. Some are 
fond of attributing the different dreaks in clays to fome mineral 
underneath, which fends up its deams, and fo changes and impreg- 
nates the clay , but if thefe dreaks do not exhibit any proof of a 
mineral impregnation, as I imagine they oftentimes do not, then thefe 
variegations cannot be owing to the caufe affigned ; and indeed 
even where thefe dreaks appear to be impregnated, I fhould rather 
chufc to attribute the alteration to the mineral or metallic particles 
brought downwards by rain or brook, than upwards by deam ; for 
though mineral deams will rife into the air and water, and the va- 
cuities or done, yet this afcent cannot be copious enough to impreg- 
nate bodies of clay ten, twenty, and thirty fathom deep : the truth 
is, we cannot always fay what particular colours are primarily owing 
to ; but we find by experiment, that portions of different coloured 
earth, reduced to a thin pade, poured gently into one veffel at dif- 
ferent times, will produce veins and eddies in clay ; and doubtlefs 
the fame procefs gave the dreaks to clays and marbles. 
CHAP. VII. 
Of the Sands in Cornwall. 
C ORNWALL, furrounded as it is on the South, Wed, and sect.i. 
North, by the Sea, has perhaps a greater variety of fea-fands Sands, the 
than any County in Great Britain ; fo many fandy coves it has on o°rigine? d 
\ Since my writing the above, I find the fol- 
lowing paffage in Bilhop Pontoppidan’s Natural 
Hiitory of Norway, Part i. “ Of the dark-green 
tt * s bkewife ufed for calling variety 
°f foy es ’ t have feen images, and other kinds 
of fculpture with as fine a polilh, and in every 
“ refpedl as fightly, as if of marble or ferpentine j 
“ yet the latter would have taken up thrice the 
“ labour and time, for the talc ftone, efpecially of 
“ a good kind is worked much eafier than wood 
« itfelf.” 
1 Dr. Plot, Oxfordfliire, page 58, he. 
every 
