384 Proceedings of the Royal Physical Society. 
larger lochs are often occupied by a colony of Common 
Gulls, or a single pair of Greater Blackbacks, or sometimes, 
when wooded, by a heronry, where the ungainly birds look 
strangely out of proportion to the stunted birch and holly 
trees in which their nests are placed. 
Immediately to the north of Loch Maree, and round the 
head of the Fionn Loch, the gneiss rises to a considerable 
height, forming the rugged mountains of Airidh a Charr, 
Ben Lair, Beinn 4 Chaisgain, and the Maighdean, whose 
mural precipices are the resort of the Golden Eagle, .the 
Peregrine, and—until within the last few years—of the 
White-tailed Erne. . 
The Torridon Sandstone, or Torridonian, as it is now called, 
rests unconformably upon the gneiss, filling up the hollows 
and lapping over the lower hills of the ancient land surface. 
It is chiefly made up of purple and chocolate-coloured gritty 
sandstones, with local developments of dark shales, flagstones, 
and basal conglomerate or breccia. These rocks occupy the 
greater part of Gairloch and Dundonnell, and nearly the 
whole of Applecross, and form some of the most striking 
scenery of the West Coast. The spiry cones of An Teallach, 
the spear-shaped crest of Slioch, the splintered ridge of 
Leagach—all rising to heights of upwards of 3250 feet— 
together with Alligin, Ben Dearg, Ben Bhan, and a host of 
minor peaks—belong to this formation ; and on their terraced 
cliffs of sandstone, whose regular bedding gives the effect of 
courses of cyclopeean masonry, most of the remaining pairs 
of Eagles, Buzzards, Peregrines, and Ravens in the district 
find a more or less secure nesting-place. 
But apart from the mountain peaks and precipices, the 
lower hill-slopes and less elevated moorlands sloping to the 
sea, that are included in the Torridonian area, have a peeuliar 
character induced by the structure of the underlying rocks. 
The successive outcrops of sandstone, horizontal or dipping 
gently in one uniform direction over large areas, form a 
. succession of terraces, flat or inclined at a low angle, that 
follow each other in parallel lines along the contour of the 
hill-slopes. On the higher ground these terraces are usually 
bare, and strewn with carried boulders. Lower down they 
