346 
BATHYMETRICAL SURVEY OF 
elevation was estimated at about 830 feet above sea-level. The bottom 
of an Gead Loch is irregular and stony, so much so that in the deeper 
part no mud could be got, while the shallow western portion is covered 
with sand. Though irregular, the basin has a flat-bottomed character, 
for the majority of the soundings were taken in depths exceeding 10 
feet, and only three soundings in depths exceeding 20 feet. The area of 
the lake-floor covered by more than 10 feet of water is about 62 acres, 
or 56 per cent, of the total area. The temperature of the water was 
nearly uniform on the date of the survey, a reading at the surface 
giving 46°*7 Fahr., and a reading at 25 feet 46°-0. 
Loch Monar (see Plate LXXXI.). — Loch Monar lies at the head 
of Glen Strath Farrar, little more than a mile to the north-east of 
an Gead Loch, and is one of the most important lochs in the Beauly 
basin. In length and in superficial area it is slightly inferior to Loch 
Mullardoch, but it is the deepest of the series, and contains the largest 
volume of water. The general trend of Loch Monar is east and west, 
but with a slight sinuosity in the outline, the length exceeding 4 miles. 
The width varies considerably, the maximum breadth of nearly half a 
mile occurring near the west end, the mean breadth of the entire loch 
exceeding a quarter of a mile. The waters of the loch cover an area 
of about 750 acres, or over one square mile, and the area draining 
directly into it is about 41 square miles, but since it receives the 
overflow from Lochs Calavie, an Tachdaidh, and an Gead, the total 
drainage area is about 50 square miles. The maximum depth of 260 
feet was observed much nearer the eastern than the western end. 
The volume of water is estimated at 3213 millions of cubic feet, and 
the mean depth at 98J feet. The loch was surveyed on October 10, 
1903, when the elevation of the lake-surface above the sea was found 
to be 663-9 feet; when levelled by the officers of the Ordnance Survey 
on June 20, 1866, the elevation was 662*8 feet above sea-level. At the 
time of the survey the water was about its normal level, and might 
rise to the extent of several feet. 
Loch Monar is quite simple in conformation, all the contour-lines 
enclosing continuous areas, and the cross-lines of soundings indicating 
a regularly sloping bottom from the shores out towards the centre of 
the loch. The longitudinal section, A-B on the map, along the centre 
of the loch from end to end shows slight undulations of the lake-floor, 
the shallowings coinciding with constrictions in the outline. The 
contour-lines all approach nearer to the eastern than to the western 
end of the loch, showing a steeper slope in an easterly direction from 
the deepest sounding, which was taken less than a mile from the east 
end, or one-fourth of the distance from one end to the other. The off- 
shore slope is in places very steep, especially along the southern shore 
at the deepest part of the loch, where near the centre of the loch a 
