298 
BATHYMETRICAL SURVEY OF 
from end to end, roughly approximating with the outline of the loch. 
The principal 50-feet basin extends from the narrows for a distance of 
three-quarters of a mile down the loch, and there is an isolated sounding 
of 52 feet to the north-west of the narrows. The 75-feet basin is a long 
and narrow area, half a mile in length, the deepest sounding having 
been recorded at the upper end of this basin, and comparatively close to 
the south-western shore, off which the slope is steep. This is well shown 
in the cross-section E-F on the map, and at other places along both 
shores the soundings indicate steep slopes. The longitudinal section 
A-B shows the shoaling of the water at the narrows, deepening 
immediately to the south-east to the maximum depth of the loch ; 
there is also a scarcely perceptible shoaling farther down the loch, 
where a sounding of 37 feet was recorded, with 47 feet to the north- 
west and 41 feet to the south-east. The areas between the consecutive 
contour-lines, and the percentages to the total area of the loch, are 
as follows : — 
0 to 25 feet 
190 acres 
43 per cent. 
25,, 50 „ 
198 „ 
45 
50 „ 75 „ 
3/ ,, 
9 
5) 
Over 75 ,, 
14 „ 
3 
>> 
439 „ 
100 
5) 
These figures show that the average slope is slightly steeper within 
the 25-feet line than between 25 and 50 feet, and they also show how 
circumscribed is the area deeper than 50 feet, 88 per cent, of the lake- 
floor being covered with less than 50 feet of water. 
Temperature Observations . — A series of temperatures taken in the 
deepest part of the loch at 6 p.m. on the date of the survey gave the 
following results ; — 
Surface . 
25 feet .. 
50 „ ., 
80 „ .. 
56° -8 Fahr. 
56°-2 „ 
56° -0 „ 
55° -8 „ 
These observations indicate a range of only 1° from surface to 
bottom. 
Loch a' Ghriama (see Plate LX VII.). — Loch a’ Ghriama (or Griam) 
lies immediately to the north of the head of Loch Shin, into which its 
waters are carried by a short rapid stream. The distance between the 
two lochs is only a quarter of a mile, and at the time of the survey 
there was a difference in level of nearly 33 feet. It is a good trout 
loch, and Salmo ferox is also found in it. The principal feeder is the 
Amhainn an Ceardaich, over a mile in length, bearing the outflow 
from Loch Merkland. It trends almost north and south, and is IJ 
