510 THE FRESH- WATER LOCHS OF SCOTLAND 
with high mountains on either side. Hence during the glacial 
period^ when the ice-shed was independent of the present watershed, 
such valleys received a larger volume of ice than could have been 
obtained from their own catchment basins. It is evident that such 
was the case with Loch Shell, for the lake deepens at its head 
where the valley becomes constricted, and the deep basin is con- 
tinued till the valley widens at the foot and the lake bends towards 
the west. A depression of 20 feet would convert Loch Shell into 
a typical fiord, and a depression of a little over 50 feet would unite 
it with Loch Eil and transform the districts of Ardgour, Morvern, 
and Ardnamurchan into an island. The head of Loch Shell has been 
partly silted up by the Finnan and Gallop and by the deposits of 
the 50-ft. beach. 
Shin. — Typical valley rock-basin in granulitic Moine schists, with several 
minor basins, some of which are probably separated by rocky 
barriers ; but one of them is certainly produced by the delta of 
the river Skiag extending below water nearly across the loch, and 
forming a favourite fishing-ground. At Shinness the lake branches 
into Loch Vanavie, a shallow tributary among moraines. Loch 
Shin lies along the principal outlet from the Mid-Sutherland 
ice area. 
Shurrery. — Partly a rock-basin in Caithness flagstones and partly drift- 
dammed. 
SioR LocHs. — Shallow lochs ponded by drift in hollows of volcanic rocks 
of the Lorne plateau. 
Skae. — Partly in Silurian greywackes and partly drift-dammed. 
Skaill. — Rock-basin in Old Red flagstones. 
Skealtar. — Rock-basin in Lewisian Gneiss. 
Skebacleit. — Rock-basin in Lewisian Gneiss. 
Skeen (Annan basin). — Ponded by moraines in corrie or coomb in grey- 
wackes and shales (see Sir A. Geikie's Scenery of Scotland, 3rd edit., 
p. 349). 
Skene (Dee basin). — Ponded by drift resting upon granite. 
Skerrow. — Partly a rock-basin and partly in drift on granite of Cairns- 
more of Fleet massif 
Skiach. — Partly in schist and partly drift-dammed. 
Skinaskink. — A rock-basin in Lewisian Gneiss and Torridon Sandstone. 
It contains several minor basins. 
Slag A IN, an t-. — Rock-basin in Torridon Sandstone, partly ponded by drift. 
Snarravoe.— Rock-basin in crystalline schists and metamorphic lime- 
stones, partly drift-dammed. 
Soulseat.— Kettle-hole in fluvio-glacial beds on lOO-ft. raised beach. 
Spiggie. — Impounded by a barrier of blown sand lying across the mouth 
of a shallow valley floored by boulder clay, which rests on granite, 
schist, and Old Red Sandstone. It is separated from Loch Brow 
by a delta laid down by the Burn of Hill. 
