yards, it migrates into a variety of arnygda-
loid, fome dark green and hard, others
ochre yellow, with globules of green earth}
and is as foft as clay*
It is very probable this fubftancSe Was
at fome early period equally hard; but from
being fo differently . expofed to the adiott
of the atmofphere, is in fome places covered
with vegetable earth, mofs, &c. and in other
places it may receive the filtrated water
from the limeftone ftratum, which perhaps
may, in fome degree, be the caufe of its
various appearances.*
It is not confidered as a ftratum that admits
of water filtrating through it, though for
a fmall depth it is penetrated by it; fprings
* This flratum is confidered by the miners' as very
■ uneven ; it by no means fo frequently divides the limeftone
and veins of ore as is imagined; a number o f mines
from 50 to 80 fathom deep are fituated in the limeftone,
•where the toadftone has not been met with. In fadt, it may
be ftated feldom to occur inftead o£ generally.
often
often appear on its furface. Tfo give an
exad account of the variety of appearances
this fubftance takes in the fame ftratum,
Would be too extenfive for a work like
this, neither is it to be fuppofed every place
is mentioned, where it and the preceding
ftrata, make. their appearance. This is intended
to give a concife defcription of thofei
only that have been under my obfervation,
more particularly in the neighbourhood of
\
Caftleton.
SECTION