35 ° 
THE TERTIARY VOLCANOES 
BOOK VIII 
would not fail to notice that it is among the northern hills of the island 
that the bedded character is so conspicuous, and that it ceases to he promi- 
nent in the southern heights, though here and 
there, as in the upper part of Scuir na Gillean, it 
may in certain lights be detected even from a 
distance. Crossing over from Eigg, he would re- 
cognize each of the features represented in the 
sketch reproduced in Fig. 339. Along the shore, 
red sandstones rise in naked cliffs, from the top 
of which the ground slopes upward in brown 
moors to the bare rocky declivities. A deep 
valley (Glen Dibidil) is seen to run into the heart 
of the hills, between the bedded group to the north 
and the structureless group to the south. If the 
weather is favourable, some eight or more promi- 
nent parallel bars of rock may he counted on the 
two higher cones to the right. These bars are 
not quite level, but slope gently from right to 
left. They remind one of the terraced basalts of 
the plateaux, but present a massiveness and a 
breadth of intervening bare talus-slope such as are 
not usual among those rocks. 
Nor is this impression of regularity and 
bedded arrangement lessened when we actually 
climb the slopes of the hills. I had for years been 
familiar with the outlines of Rum as seen from 
a distance, and had sketched them from every side, 
but I shall never forget the surprise and pleasure 
when my first ascent of the cones revealed to me 
the meaning of these parallel tiers of rock. I 
found it to be the structure of the Cuillin Hills 
repeated, but with some minor differences which 
are of interest, inasmuch as they enlarge our 
conceptions of the process by which the gabbro- 
bosses were formed. 
The northern half of the island of Rum 
consists almost entirely of red sandstone, which, 
as already stated, is a continuation of the same 
formation (Torridonian) so well developed in the 
south-east of Skye, Applecross and Loch Torridon, 
and traceable between the Archsean gneiss and the 
Cambrian strata up as far as Cape Wrath. The 
sandstones, though full of false bedding, show quite 
distinctly their true stratification, which is inclined 
with singular persistence towards W.N.W., at angles averaging from 15° to 
20°. If they are not repeated by folds or faults, they must reach in this 
o 
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