THE FRESH- WATER LOCHS OF SCOTLAND. 13 



in greatest width. At the upper end of the loch, where the river 

 Balvag enters, there is a long spit formed of detritus brought down by 

 the river, and this end of the loch for a distance of three-quarters of a 

 mile is very shallow, while at the lower end the 50-feet contour is 

 found within 200 yards of the outlet. The area between the 50-feet 

 and 100-feet contours is estimated at about 162 acres, or 26 per cent, of 

 the total area of the loch, while the area with depths under 50 feet is 

 estimated at about 397 acres, or 65 per cent, of the area of the loch. 



When the loch was visited on April 6, 1899, it appeared from marks 

 on the shore that the water had lately been 4 feet 10 inches higher than 

 at that time, and it has been known to have been 12 or 18 inches lower, 

 so that the rise and fall is about 6 feet in all. On one occasion a disc 

 was visible down to a depth of 17 ^ feet, and on another down to 20 J feet. 



On the western shore, between 1J and 1J miles from the southern 

 end of the loch, there is a remarkable sandy spit, which stretches out 

 towards the centre of the loch, the origin of which appears to us some- 

 what puzzling (see the Geological Notes by Messrs. Peach and Home). 



Loch Chun (see Plate VIII.). There are two lochs in Perthshire bear- 

 ing this name, the one a little loch in the parish of Blair Atholl. The 

 Loch Chon now_ under consideration lies to the south of Loch Katrine, 

 and trends in a north-west and south-east direction. It lies at a height 

 of 296 feet above sea-level, and the river into which it flows expands, a 

 little distance to the south-east, into the small loch, Lochan Dubh or 

 Loch Dhu, the surface of which is 10 feet lower. Loch Chon is over 

 In miles in length, and the greatest width is about one-third of a mile. 

 The mean breadth, obtained by dividing the area of the loch by its 

 length, is a quarter of a mile, being 15 per cent, of the length. Its 

 waters cover an area of about 277 acres, or less than half a square mile, 

 and it drains an area about 14i times greater, or nearly 4000 acres 

 (nearly 6 J square miles) . The number of soundings taken in Loch Chon 

 was 157, the greatest depth observed being 75 feet. The mass of water 

 contained in the loch is estimated at 358,000,000 cubic feet, and the 

 mean depth at over 29 feet, or 39 per cent, of the maximum depth. The 

 length of the loch is 120 times the maximum depth, and 305 times the 

 mean depth. 



Loch Chon is irregular in outline, and the contour-lines are also 

 irregular. The deepest part of the loch (i.e. exceeding 50 feet) forms a 

 long, narrow depression, situated approximately in the centre of the 

 loch, but closer to the western than to the eastern shore, about seven- 

 twelfths of a mile in length, with a maximum width of over one-sixth of 

 a mile. The maximum depth, 75 feet, was found comparatively very 

 close to the western shore, being in fact only about 130 yards distant; 

 this gives a slope of almost 1 in 5, and a similar steep slope is indicated 

 by the near approach to the shore of the contour-lines for a considerable 



