The Old Red Sandstone; or, New Walks in an Old Field
John Stuart Mill · en
Some of the springs which issue from the ichthyolite beds along
the shores of the Moray Frith are largely charged, not with iron,
like the well of the coal-heugh, or the springs of Tarbat House,
nor yet with hydrogen and soda, like the spa of Strathpeffer, but
with carbonate of lime. When employed for domestic purposes, they
choke up, in a few years, with a stony deposition, the spouts of
tea-kettles. On a similar principle, they plug up their older
channels, and then burst out in new ones; nor is it uncommon
to find among the cliffs little hollow recesses, long since
divested of their waters by this process, that are still thickly
surrounded by coral-like incrustations of moss and lichens, grass
and nettle-stalks, and roofed with marble-like stalactites. I am
acquainted with at least one of these springs of very considerable
volume, and dedicated of old to an obscure Roman Catholic saint,
whose name it still bears, (St. Bennet,) which presents phenomena
not unworthy the attention of the young geologist. It comes gushing
from out the ichthyolite bed, where the latter extends, in the
neighborhood of Cromarty, along the shores of the Moray Frith;
and after depositing in a stagnant morass an accumulation of a
grayish-colored and partially consolidated travertin, escapes by
two openings to the shore, where it is absorbed among the sand and
gravel. A storm about three years ago swept the beach several feet
beneath its ordinary level, and two little moles of conglomerate
and sandstone, the work of the spring, were found to occupy the two
openings. Each had its fossils--comminuted sea-shells, and stalks
of hardened moss; and in one of the moles I found imbedded a few
of the vertebral joints of a sheep. It was a recent formation on a
small scale, bound together by a calcareous cement furnished by the
fish-beds of the inferior Old Red Sandstone, and composed of sand and
pebbles, mostly from the granitic gneiss of the neighboring hill, and
organisms, vegetable and animal, from both the land and the sea.