Millstone Grit
See also:
millstone grit
English
Noun
Millstone
Grit
(
uncountable
)
(
geology
)
A
group
of
coarse-grained
sandstone
from the
Carboniferous
period
,
primarily
found
in the
British Isles
.
Further reading
Millstone Grit
on Wikipedia.
Wikipedia