156 
BATHYMETRICAL SURVEY OF 
LOCHS OF THE ROE BASIN. 
The two principal lochs only in this basin, Lochs Crocach and an Tuirc, 
were surveyed ; the smaller ones could not be sounded from lack of 
boats. 
Loch Crocach (see Plate XXXVII.). — Loch Crocach lies about three 
miles to the north of Loch Inver, and about a mile to the north-west of 
Loch an Tuirc, into which its waters are discharged. It is most 
irregular in outline and in conformation, and is studded with islands 
large and small; indeed the insulosity (Le., the ratio between the area 
of the islands and the total area of the loch) is one of its distinguishing 
characteristics, being probably higher than in any other loch visited by 
the Lake Survey, the lochs most nearly approaching it in this respect 
being Lochs Maree and Lomond. The islands are mostly congregated 
in the large western bay; they are low, heather-covered, and not 
wooded as in the majority of the lochs in the district. The ground 
around the loch is low; from 350 to 700 feet above the sea. Loch 
Crocach trends north-east and south-west, and is nearly IJ miles in 
length and over one-third of a mile (or about 700 yards) in maximum 
breadth, the mean breadth being about one-sixth of a mile (or rather 
less than half the maximum breadth). Its waters cover an area of 
about 160 acres (or one-quarter of a square mile), exclusive of the 
numerous islands, and it drains an area seven times greater, or 1| square 
miles. Nearly 80 soundings were taken, the maximum depth observed 
being 71 feet. The volume of water is estimated at 147,987,000 cubic 
feet, and the mean depth at nearly 17 feet. Loch Crocach is deeper 
than the other small lochs in this district. A large 25-feet area occupies 
the greater portion of the length of the loch to the north-west of the 
islands ; a second smaller area occurs in the south-western expansion of 
the loch, and a third very small area lies near the south-western end 
of the loch, based on a sounding of 30 feet. The bottom falls in two 
places below the 50-feet level, the larger basin being centrally placed, 
between the entrance of the Uidh nan Lion and the largest of the 
islands, with a maximum depth of 64 deet, the smaller but deeper basin 
lying in the south-western expansion of the loch, the maximum depth 
of 71 feet having beeii observed quite close to the small island off the 
