CHAP. XXXVIII 
RIVERS OF THE PERIOD 
237 
terminating on the north-west at the edge of the great sea-cliff (975 
feet), and ending off on the south-east in that strange well-known mountain- 
wall (1272 feet high) which rises in a sheer cliff nearly 300 feet above the 
basalt-plateau on the one side and more than 400 feet on the other (Tig. 278). 
The total length of the Seuir ridge is two miles and a quarter, its greatest 
breadth 1520, its least breadth 350 feet. Its surface is very irregular, 
rising into minor hills and sinking into rock-basins, of which nine are small 
tarns, besides still smaller pools, while six others, also filled with water, lie 
partly on the ridge and partly on the basaltic plateau. No one, indeed, 
who looks on the Seuir from below, and notes how evenly it rests upon the 
basalt-plateau, would be prepared for so rugged a landscape as that which 
meets his eye everywhere along the top of the ridge. Two minor arms pro- 
Fig. 278.— View of the Seuir of Eigg from the east. 
ject from the east side of the ridge ; one of these forms the rounded hill 
called Beinn Tighe (968 feet), the other the hill of A ehor Bheinn. 
Singular as the Seuir of Eigg is, regarded merely as one of the land- 
marks of the Hebrides, its geological history is not less peculiar. The 
natural impression which arises in the mind when this mountain comes into 
view for the first time is, that the huge wall is part ot a great dyke or intrusive 
mass which has been thrust through the older rocks. 1 It was not until after 
some time that the influence of this first impression passed off my own mind, 
and the true structure of the mass became apparent. 
The ridge of the Seuir, presenting as it does so strong a topographical 
1 Hay Cunningham remarks “ In regard to the relations of the pitchstone-porpliyry of the 
Seuir and the trap-rocks with which it is connected, it can, after a most careful examination' 
around the whole mass, be confidently asserted that it exists as a great vein which has been 
erupted through the other Plutonic rocks— thus agreeing in age with all the other pitchstones 
of the island.” Maoeulloch leaves us to infer that he regarded the rock of the Seuir to be 
regularly interstratified with the highest beds of the dolerite series ( Western Isles, i. p. 522). 
Hugh Miller speaks of the Seuir of Eigg as “resting on the remains of a prostrate forest.”- 
Cruise of the Betsy , p. 32. 
