THE OLD RED SANDSTONE. 185 
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 in- 
crustations 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 ded- 
icated of old to an obscure Roman Catholic saint, whose name 
it still bears, (St. Bennet,) which presents phenomena not un- 
worthy the attention of the young geologist. It comes gush- 
ing 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 accumu- 
lation of a grayish-colored and partially consolidated traver- 
tin, 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 fur- 
nished 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. 
