re presented by the igneous masses of
Skye, Ardnamurchan, and Mull towards the west. Rain and river action,
supplemented by that of glaciers, have also had a share in eroding
channels and wearing down the upper surface of the ground, with the
result we at present behold in the wild and broken scenery of the Inner
Hebrides and adjoining coast.

[1] Geikie, _loc. cit._, p. 178; also _Quart. Jour. Geol. Soc._, vol.
xxvii. p. 303.

CHAPTER VI.

ISLE OF STAFFA.

Reference has been made to this remarkable island in a former page, but
some more extended notice is desirable before leaving the region of the
Inner Hebrides. Along with the islands of Pladda, Treshnish, and
Blackmore, Staffa is one of the outlying volcanic islands of the group,
being distant about six miles from the coast of Mull, and indicates the
minimum distance to which the plateau-basaltic sheets originally
extended in the direction of the old marginal lands of Tiree and Coll.
The island consists of successive sheets of bedded basaltic lava, with
partings of tuff, one of which of considerable thickness is shown to lie
at the base of the cliff on the south-west side of the island.[1] The
successive lava-sheets present great varieties of structure, like those
on the north coast of Antrim; some being amorphous, others columnar,
with either straight or bent columns. The lava-sheet out of which
Fingal's Cave is excavated consists of vertical prisms, beautifully
formed, and surmounted by an amorphous mass of the same material. At the
entrance of the Boat Cave we have a somewhat similar arrangement of the
columns;[2] but at the Clam-shell Cave the prisms are curved, indicating
some movement in the viscous mass before they had been fully
consolidated.

Fingal's Cave is called after the celebrated prince of Morvern (or
Morven), a province of ancient Caledonia. He is supposed to have been
the father of Ossian, the Celtic bard rendered famous by Macpherson. The
cave, one of many which pierce the coast-cliffs of Western Scotland, is
227 feet in length, 166 feet in height, and 40 feet in width. On all
sides regular columns of basalt, some entire, others broken, rise out of
the water and support the roof. The cave is only accessible in calm
weather.

[1] A drawing of this cliff is given by Geikie in the _Manual of
Geology_ (Jukes and Geikie), 3rd edition, p. 277.

[2] Prestwich, _Geology_, vol. i. p. 281, where a view of this cave is
given.

PART V