s,--the remains of
fucoids, too, of great size and in vast abundance. Mr. Dick has
disinterred from among the rocks of Sanday Bay flattened carbonaceous
stems four inches in diameter. We are still within an hour's walk of
Thurso; but in that brief hour how many marvels have we witnessed!--how
vast an amount of the vital mechanisms of a perished creation have we
not passed over! Our walk has been along ranges of sepulchres, greatly
more wonderful than those of Thebes or Petraea, and mayhap a thousand
times more ancient. There is no lack of life along the shores of the
solitary little bay. The shriek of the sparrow-hawk mingles from the
cliffs with the hoarse deep croak of the raven; the cormorant on some
wave-encircled ledge, hangs out his dark wing to the breeze; the spotted
diver, plying his vocation on the shallows beyond, dives and then
appears, and dives and appears again, and we see the silver glitter of
scales from his beak; and far away in the offing the sunlight falls on a
scull of seagulls, that flutter upwards, downwards, and athwart, now in
the air, thick as midges over some forest-brook in an evening of
midsummer.

But we again pass onwards, amid a wild ruinous scene of abrupt faults,
detached fragments of rocks, and reversed strata: again the ledges
assume their ordinary position and aspect, and we rise from lower to
higher and still higher beds in the formation,--for such, as I have
already remarked, is the general arrangement from west to east, along
the northern coast of Caithness, of the Old Red Sandstone. The great
Conglomerate base of the formation we find largely developed at Port
Skerry, just where the western boundary line of the county divides it
from the county of Sutherland; its thick upper coping of sandstone we
see forming the tall cliffs of Dunnet Head; and the greater part of the
space between, nearly twenty miles as the crow flies, is occupied
chiefly by the shales, grits, and flagstones, which we have found
charged so abundantly with the strangely-organized ichthyolites of the
second stage of vertebrate existence. In the twenty intervening miles
there are many breaks and faults, and so there may be, of course,
recurrences of the same strata, and re-appearances of the same beds;
but, after making large allowance for partial foldings and repetitions,
we must regard the development of this formation, with which the twenty
miles are occupied, as truly enormous. And yet it is but one of three