structure unchanged.
Surely a curious chemistry, and conducted on an enormous scale!

It had been an essential part of my plan to explore the splendid section
of the Lower Oolite furnished by the line of sea-cliffs that, to the
north of the Portree, rise full seven hundred feet over the beach; and
on the morning of Wednesday I set out with this intention from Isle
Ornsay, to join the mail gig at Broadford, and pass on to Portree,--a
journey of rather more than thirty miles. I soon passed over the gneiss,
and entered on a wide deposit, extending from side to side of the
island, of what is generally laid down in our geological maps as Old Red
Sandstone, but which, in most of its beds, quite as much resembles a
quartz rock, and which, unlike any Old Red proper I have ever seen,
passes, by insensible gradations, into the gneiss.[2] Wherever it has
been laid bare in flat tables among the heath, we find it bearing those
mysterious scratches on a polished surface which we so commonly find
associated on the mainland with the boulder clay; but here, as in the
Hebrides generally, the boulder clay is wanting. To the tract of Red
Sandstone there succeeds a tract of Lias, which, also extending across
the island, forms by far the most largely-developed deposit of this
formation in Scotland. It occupies a flat dingy valley, about six miles
in length, and that varies from two to four miles in breadth. The dreary
interior is covered with mosses, and studded with inky pools, in which
the botanist finds a few rare plants, and which were dimpled, as I
passed them this morning, with countless eddies, formed by myriads of
small quick glancing trout, that seemed busily engaged in fly-catching.
The rock appears but rarely,--all is moss, marsh, and pool; but in a few
localities on the hill-sides, where some stream has cut into the slope,
and disintegrated the softer shales, the shepherd finds shells of
strange form strewed along the water-courses, or bleaching white among
the heath. The valley,--evidently a dangerous one to the night
traveller, from its bogs and its tarns,--is said to be haunted by a
spirit peculiar to itself,--a mischievous, eccentric, grotesque
creature, not unworthy, from the monstrosity of its form, of being
associated with the old monsters of the Lias. Luidag--for so the goblin
is called--has but one leg, terminating, like an ancient satyr's, in a
cloven foot; but it is furnished with two arms, bearing hard fists at
the en