THE FRESH- WATER LOCHS OF SCOTLAND. 253 



LOCHS OF THE NAN UAMH BASIN. 



THE lochs to be dealt with here are Loch Dubh, between the head of 

 Loch Ailort and the head of Loch nan Uamh, and Lochs Mama and 

 na Creige Duibhe lying to the north-east. Loch Doir' a' Gherrain in 

 Ardnish could not be sounded, because there was no boat on it at the 

 time of the visit of the Lake Survey. 



Loch Dubh (see Plate LVL). Loch Dubh is a small loch situated 

 at the head of the peninsula of Ardnish, which separates Loch Ailort 

 from Loch nan Uamh, the two branches of the sound of Arisaig. The 

 Mallaig extension of the West Highland railway runs along its southern 

 shore, and the outfall flows through the old bed of the little Lochan 

 Deabhta, which has been completely drained by the railway, leaving 

 only a channel through it for the escape of the waters from Loch Dubh. 

 After leaving Lochan Deabhta the outfall joins the Schoolhouse burn, 

 which has been deflected, thence into the Arnabol burn, falling into 

 the head of Loch Beag, an inlet of Loch nan Uamh. It is surrounded, 

 except on the western side, by low though steep hills, which impart 

 a dark and sullen appearance to the loch, hence its name the Black 

 loch. Considering its superficial area, it is the deepest loch visited by 

 the Lake Survey.* Its great depth, and the remarkable temperature 

 conditions discovered in it, well repaid the trouble pf carting a boat 

 from Loch nan Uamh and carrying it down to the loch. Its catchment 

 area is very small, and it would seem that the unpleasant taste of its 

 water, resembling that of a stagnant pool, is due to the small amount 

 of fresh water entering it. This unpleasantness is probably something 

 more than mere taste, for attempts to stock the loch with trout have 

 been unsuccessful, the fish rapidly dying ; eels, however, abound in it. 



Loch Dubh trends in a north-west and south-east direction, the 

 broadest part being rather nearer the south-east end. Its length is 



* The deepest lake in East Prussia is, according to Halbfass (Globus, Bd. 86, p. 187, 

 September 15, 1904), the Wuchsnigsee, which is about 1J miles in length, and has a 

 maximum depth of about 210 feet. Loch Dubh is less than half a mile in length, and its 

 maximum depth is 153 feet. 



