THE FRESH- WATER LOCHS OF SCOTLAND. 299 



miles in length, nearly uniform in width, the maximum breadth being 

 over a third of a mile, and the mean breadth over a quarter of a mile. 

 Its waters cover an area of about 260 acres, and it drains directly an 

 area of over 6^ square miles; but since it receives the outflow from 

 Loch Merkland, its total drainage area is over 22| square miles an 

 area 57 times greater than that of the loch. The maximum depth 

 of 64 feet was observed approximately in the centre of the loch, 

 but rather nearer the northern than the southern end. The volume 

 of water is estimated at 314 million cubic feet, and the mean depth 

 at 28 feet. The loch was surveyed on September 1, 1902, when the 

 elevation of the lake-surface above the sea was found to be 303*7 feet, 

 which is almost identical with the elevation observed by the Ordnance 

 Survey officers on July 4, 1856, viz. 303-5 feet. 



The conformation of Loch a' Ghriama is simple, with one or two 

 very slight undulations of the lake-floor, the principal of which gives 

 rise to a striking sinuosity in the 50-feet contour ; otherwise the contour- 

 lines coincide approximately with the outline of the loch. The 25-feet 

 basin is about 1J miles, and the 50-feet basin over half a mile, in length. 

 The longitudinal section C-D, and the cross section G-H taken at the 

 position of the deepest sounding, show generally a gradual slope down 

 to the greatest depth, and this is borne out by the following table, 

 giving the areas between the contour-lines and the percentages to the 

 total area of the loch : 



to 25 feet 121 acres 47 per cent. 



25 50 106 41 



Over 50 30 12 



257 .. 100 



Temperature Observations. The following series of temperatures, 

 taken at 3 p.m. on September 1, 1902, in the deepest part of Loch a' 

 Ghriama, indicates a range of only 2 from surface to bottom : 



Surface 57'OFahr. 



25 feet 56'2 



55 ... / 55-0 



Loch Fiodhaig (see Plate LXVIIL). Loch Fiodhaig (or Fiodiag, or 

 Fiag) lies to the north-east of the head of Loch Shin, into which its 

 superfluent waters are carried by the river Fiodhaig (or Fiag). This is 

 a good trout loch, but the fishing is preserved, surrounded by moorland 

 hills, with Ben Hee rising to the north. It receives the outflow from 

 Loch a' Ghorm-Choire and another smaller loch lying to the north, 

 which were not sounded. The loch trends in a north and south 

 direction, and is over 1^ miles in length, with a maximum breadth 

 near the northern end of two-thirds of a mile. Its waters cover an 



