THE FRESH-WATER LOCHS OF SCOTLAND. 
319 
These observations show an extreme range throughout the loch 
amounting to 7°*5, but the greater part of this range was observed 
beyond the depth of 100 feet in the deepest part of the loch, the range 
from the surface down to 100 feet not exceeding 1°*4. In the southern 
shallower basin the temperature varied little down to the bottom in 
135 feet, there being no decrease in temperature beyond 100 feet, 
whereas at a depth of 135 feet in the northern deeper basiii the tem- 
perature was 4°-5 lower than at a similar depth in the southern basin, 
and the temperature at the bottom of the deeper basin was 6° lower 
than anything observed in the shallower basin. 
Loch Greagach (see Plate LXXV.). — Loch Creagach (or Craggie) lies 
immediately to the north of Loch Laoghal and at the same level, the 
short stream between them having a slight current flowing from Loch 
Laoghal into Loch Creagach. At the north end of Loch Creagach there 
is a small expansion of the outflowing river, called Loch Slaim (or 
Slam), which was not sounded. The general trend of Loch Creagach is 
nearly north and south, with a slight bend in the outline, the northern 
portion running towards the north-east. It is over IJ miles in length, 
with a maximum width in the southern portion of half a mile. Its 
waters cover an area of nearly 300 acres, or nearly half a square mile, 
and it drains directly an area of 1| square miles; but since it receives 
the outflow from Lochs Laoghal and Cuil na Sithe, its total drainage 
area is nearly 35 square miles. The maximum depth of 84 feet was 
observed near the middle of the loch. The volume of water is estimated 
at 429 million cubic feet, and the mean depth at 33 feet. The loch 
was surveyed on September 27, 1902, when the elevation of the lake- 
surface was found to be identical with that of Loch Laoghal, viz. 369'9 
feet above the sea; when levelled by the Ordnance Survey officers on 
August 27, 1870, the elevation was 369’2 feet above sea-level, as in 
the case of Loch Laoghal. 
Loch Creagach resembles Loch Laoghal in that it contains two deep 
basins, which are separated by shallower water at the position of the 
constriction in the outline of the loch towards the northern end. The 
deeper basin occupies the wide southern portion of the loch, towards 
the peninsula separating this loch from Loch Laoghal, in which also 
the deeper water approaches the dividing peninsula, suggesting that 
at one time the two lochs may have formed a continuous sheet of water. 
The principal 50-feet area is about three-quarters of a mile in length, 
distant less than a quarter of a mile from the southern end of the loch. 
Within this basin there is a small elevation covered by 47 feet of water 
in the widest part of the loch towards the eastern shore. The maximum 
depth of the loch (84 feet) occurs a short distance to the north of this 
elevation, and about three-quarters of a mile from both ends, but 
towards the western shore, as will be seen in cross-section C-D on the 
