CHAP. XXXVIII 
RIVERS OF THE PERIOD 
243 
Eigg in the tourist-steamer that the Scuir is in no sense of the word a 
dyke. 
Hut although the Scuir is thus a bedded mass, the bedding is far 
different from the regularity and parallelism of that which obtains among 
the bedded basalt-rocks below. Even where no intervening “ porphyry ” 
occurs, the pitchstone can be recognized as made up of many beds, each 
marked by the different angle at which its columns lie. And when the 
“ porphyry ” does occur and forms so striking a division in the pitchstone, 
its beds die out rapidly, appearing now on one horizon, now on another, 
along the face, of the cliffs, and thickening and thinning abruptly in short 
distances along the line of the same bed. Perhaps the best place for 
Fig. 281. — View of the Scuir of Eigg from the South-west of the Loch a’ Bhealaich, 
showing the bedded character of the mass. 
examining these features is at the Bhealaich, the only gully practicable for 
ascent or descent, at the south-eastern face of the ridge. 
By much the larger part of the mass of the Scuir consists of vitreous 
material. As a rule this rock is columnar, the columns being much 
slimmer and shorter than those of the basalt-rocks. They rise sometimes 
vertically, and often obliquely, or project even horizontally from the 
face of tire cliff. They are seldom quite straight, but have a wavy out- 
line ; and when grouped in knolls here and there along the top of the 
ridge they remind one of gigantic bunches of some of the Palaeozoic 
corals, such as Lithostrotion. In other cases they slope out from a common 
centre, and show an arrangement not very unlike that of a Highland 
peat-stack. 
The pitchstone of the Scuir differs considerably in petrographical 
character from other pitclistones of the island which occur in dykes and 
veins. Its base is of a velvet-black colour, and is so much less vitreous 
in aspect than ordinary pitchstone as to have been described by Jameson 
