r A. Geikie in assigning to the granite of the
Mourne Mountains, and the representative felsitic rocks of the
Carlingford Mountains, a Tertiary age--in which case the analogy between
the volcanic phenomena of the Inner Hebrides and of the North-east of
Ireland would seem to be complete.[5]

[1] Geikie, _Proc. Roy. Soc. Edinburgh_ (1867); _Brit. Assoc. Rep._
(Dundee, 1867); "Tertiary Volcanic Rocks of the British Isles," _Quart.
Journ. Geol. Soc._, vol. xxvii. p. 279; also, "History of Volcanic
Action in British Isles," _Trans. Roy. Soc. Edin._ (1888); Judd, "On the
Ancient Volcanoes of the Highlands," etc., _Quart. Journ. Geol. Soc._,
vol. xxx. p. 233; and _Volcanoes_, p. 139.

[2] _Brit. Assoc. Rep._ for 1850, p. 70.

[3] Judd, _Quart. Jour. Geol. Soc._, vol. xxx. p. 242.

[4] _History of Volcanic Action, etc._, _loc. cit._ p. 153, _et seq._
The "Granophyres" of Geikie come under the head of "Felsites," passing
into "granite" in one direction and quartz-trachyte in another,
according to Judd; the proportion of silica from 69 to 75 per
cent.--_Quart. Jour. Geol. Soc._, vol. xxx. p. 235.

[5] This view the author has expressed in a recent edition of _The
Physical Geology of Ireland_, p. 177 (1891).

CHAPTER IV.

ISLE OF SKYE.

This is the largest and most important of all the Tertiary volcanic
districts, but owing to the extensive denudation to which, in common
with other Tertiary volcanic regions of the British Isles, it has been
subjected, its present limits are very restricted comparatively to its
original extent. Not only is this evident from the manner in which the
basaltic sheets terminate along the sea-coast in grand mural cliffs, as
opposite "Macleod's Maidens," and at the entrance to Lough Bracadale on
the western coast, but the evidence is, according to Sir A. Geikie,
still more striking along the eastern coast; showing that the Jurassic,
and other older rocks there visible, were originally buried deep under
the basaltic sheets which have been stripped from off that part of the
country. These great plateau-basalts occupy about three-fourths of the
entire island along the western and northern areas, rising into terraced
mountains over 2,000 feet in height, and are deeply furrowed by glens
and arms of the sea, along which the general structure of the tableland
is laid open, sometimes for leagues at a time.

It is towards the south-eastern part of the island that the most
interesting and importa