S E C T I O N XV.
Salt Mine of Northwicb.
O N proceeding from Kutsford to North-
wich, the chief appearance is that of grit
flone, with fome nodules of granite and
clay.
A fmall diftance from Northwich I was
lowered down into the fait work, about
I io yards, by a fleam engine. The fhafts
are lined with wood ; and the firfl bed
of fait is about 40 yards thick, being excavated
about ten feet in height, to an extent
of 50 yards.
Defcending about 60 yards further, you
arrive at the bottom, which appears like a
grand
grand amphithéâtre, about 120 yards long,
loo broad, and 15 feet high. Triangular
pillars of a vaft fize fupport the roof, and
every part being perfectly dry and clean,
the effed is very pleafing.
They get the fait with long chiflels, and
by the blaft, working from the folid rock
at the fides.
The ftrata are extremely irregular. At
the furface is a ftrong red clay, then a
fhiftofe fiibftance called plate, which is followed
by a little layer of coarfe grit ; then
a blue clay with gypfum, to which fiicceeds
a fubftance called metal, being an indurated,
day* in which are veins of rock fait. This
clay is of great thicknefs, and is followed
by a bed of rock fait, workable for perhaps
20 feet. Next is a ftratum of clay,
mixed with fait* about 30 yards thick, more
or lefs impregnated, until it becomes a hard
compad rock fait, which is generally of a
M2 reddifh