THE FHESH-WATER LOCHS OF SCOTLAND. 
301 
The floor of Gorm Loch Mor is most irregular, islands and banks 
and deep soundings being found here and there in close proximity, 
while in other places deep water approaches close to the shore. The 
contour-lines are of the most sinuous description, with isolated deep 
and shallow patches. The deepest part of the loch runs along the 
western shore, off which the slope is uniformly rather steep, and occurs 
towards the north-western end, as will be seen in the longitudinal 
section A-B on the map. The areas between the contour-lines, and 
the percentages to the total area of the loch, are as follows ; — 
0 to 25 feet 
126 acres 
68 per cent. 
25 ,, 50 ,, 
35 ,, 
19 „ 
50,, 75 „ 
16 „ 
8 
Over 75 „ 
8 „ 
5 „ 
185 „ 
100 
Temperature Observations . — surface reading at 10 a.m. on October 
22, 1902, when commencing the survey, gave 44° Fahr., but at 2 p.m. 
in the deepest part of the loch a series of temperatures gave identical 
readings, viz. 46°-2, at the surface and at 10, 25, 50, and 75 feet. 
LocliAilsh (see Plate LXIX.). — ^Loch Ailsh lies about 10 miles to the 
west of Loch Shin, with the heights of Ben More Assynt and Coniveall 
rising to the north. It is a moderate-sized but rather shallow loch, 
containing trout and an occasional salmon or grilse. It is irregular in 
outline, slightly under a mile in length from north to south, with a 
maximum width in the northern portion exceeding half a mile. Its 
waters cover an area of about 245 acres, and it drains an area 44 
times greater — an area of nearly 17 square miles. The maximum depth 
of 24 feet was observed in the north-eastern part of the loch, less than 
a quarter of a mile from the alluvial cone laid down at the mouth 
of the river Oykell on the northern shore. The volume of water is 
estimated at 88 million cubic feet, and the mean depth at 8J feet. The 
loch was surveyed on September 6, 1902, when the elevation of the 
lake-surface above the sea was found to be 498'5 feet, almost identical 
with that observed by the Ordnance Survey officers on August 29, 1871, 
viz. 498’4 feet. The highest drift-mark observed was 4 feet above the 
level of the water on the date of the survey. The southern and western 
portions of Loch Ailsh are covered by less than 10 feet of water, the 
deeper part lying along the eastern shore and towards the north-eastern 
angle of the loch. The area of the lake-floor covered by less than 10 
feet of water is about 173 acres, or 71 per cent, of the entire area, while 
that covered by more than 20 feet of water is only about 12 acres, or 
5 per cent. The temperature of the surface water at 2 p.m. on the 
date of the survey was 55°*3 Fahr., and a reading at a depth of 20 feet 
gave 54°.' 
