THE FRESH-WATER LOCHS OF SCOTLAND. 63 



LOCHS OF THE ALSH BASIN. 



THE area draining into Loch Alsh and its two branches Loch Duich 

 and Loch Long is an extensive one, but only three small lochs within the 

 basin were sounded by the Lake Survey. The two more important ones, 

 Loch na Leitreach and Loch a* Bhealaich, drain by the River Elchaig into 

 the head of Loch Long ; while the third and smallest one, Loch Anna, 

 drains into the Allt Gleann Udalain, which flows into Loch Alsh on its 

 northern shore. The large area draining into Loch Duich is almost 

 entirely devoid of lakes. The scenery of the district is grand and 

 mountainous, many of the peaks exceeding 3000, and some of them 

 exceeding 3500, feet in height. 



Loch na Leitreach (see Plate XXIIL). Loch na Leitreach lies about 

 six miles east of the head of Loch Long, and about the same distance 

 north-east of the head of Loch Duich. It trends in a south-west and 

 north-east direction, and is widest towards the north-eastern end, narrow- 

 ing gradually towards the outflow at the south-western end. It exceeds 

 a mile in length, with a maximum breadth of one-fifth of a mile, the 

 superficial area being about 84 acres. The area draining into it is about 

 12 square miles, including Loch Muirichinn (not surveyed) lying at the 

 head of the glen at a high elevation. The maximum depth of 88 feet was 

 observed near the middle of the loch. The volume of water is estimated 1 

 at 147 million cubic feet, and the mean depth at over 40 feet. The 

 formation of the main basin is simple, the deeper water occupying the 

 wide upper portion of the loch, a depth of 65 feet having been recorded 

 close to the upper end, and the maximum depth of 88 feet about half a mile 

 down the loch. Xear the south-west end a depth of 31 feet was found, 

 separated from the main basin by depths of 14 and 15 feet. 



The loch was surveyed on October 10, 1904, when the elevation was 

 supposed to be about 275*3 feet above the sea, that is to say, the water just 

 covered the position indicated on the 6-inch Ordnance Survey map for a 

 bench-mark placed at that altitude on the south side of the road at the 

 north angle of the loch. The temperature of the water was practically 

 uniform, the reading at the surface being 46 7 '2 Fahr., and at a depth of 80 

 feet 46-0. 



Loch a' Bhealaich (see Plate XXIV.). Loch a' Bhealaich lies about 4 

 miles east of the head of Loch Dutch, and 3^ miles south of Loch na 



