THE FRESH-WATER LOCHS OF SCOTLAND. 
211 
The geology of this district is described by Drs. Peach and Horne, 
their important contribution being illustrated by a special geological 
map. 
Loch Maree (see Plates XL VI. and XL VII.). — The loch derives its 
name from Saint Maelrubha, who in 671 a.d. left Bangor, and after 
founding one church at Applecross, founded another on Isle Maree. 
It is the largest sheet of fresh water in Scotland north of Loch Ness, 
and trends in a north-west and south-east direction. 
On the north-east side of the loch, and parallel to it, runs a grand 
series of mountains — ^Beinn Airidh Charr, Meall Mheannidh, Beinn 
Lair, Slioch, Sgurr an Tuill Bhain, and Beinn a Mhuinidh ; the slope 
for the first 1000 feet all along this north-eastern shore is very steep, in 
many places exceeding 45°. To the south-west rise Beinn Eighe, Beinn 
a Chearcaill, and Beinn an Eoin ; the sharp ridge of the former, com- 
posed of white quartzite, forms an especially fine object from the loch to 
the north of the Gruididh, But the two most striking features of Loch 
Maree are Slioch and Isle Maree ; the huge sugar-loaf form of Slioch 
is conspicuous from almost every part of the loch, and, though one of 
the smaller islands. Isle Maree, owing to the large number of trees 
growing upon it, stands out against the dark background of the heather- 
covered islands and the cliffs of the north-eastern shore. 
The great feature of Loch Maree is the large number and great 
area of its islands. Prof. Penck, in his work on the Lake of Constance, 
lays great stress on the ' ' insulosity, ” Le., ‘‘the proportion of the area 
of the islands to that of the water surface ; ” this in Loch Maree is 0*09, 
or three times as great as that of the Lake of Cheim (0*03), and nine 
times as great as that of the Lake of Constance (0*01). Its insulosity is 
also greater than that of any other large lake in Great Britain, that of 
Loch Lomond being 0*08, though it is surpassed in this respect by one 
of the small lochs in the Assynt district (Loch Crocach, whose insulosity 
is 0*091). 
Many of the islands were joined together when the Lake Survey 
visited the loch, owing to the low level of the water. A few small 
rocks and reefs occur out in the channel to the north of the main 
group of islands and removed some considerable distance from the rest. 
Large numbers of the Lesser Black-Backed Gull (Larus fuscus) breed 
on the larger islands, and two pairs and young of the Greater Black- 
Backed Gull (Larus marinus) were observed on two of the smaller islets. 
Isle Maree, Eilean Ghruididh, Eilean Subhainn, and Eilean Ruairid 
Bheag have been used at one time as fortresses or habitations. 
The level of Loch Maree was found by the Ordnance Surveyors to 
be 32*1 feet above sea-level on September 15, 1870; on July 16, 1902, 
the surface of the water was 29*5 feet above sea-level. The loch was 
surveyed on July 16 to 24, 1902, and the water remained at very nearly 
