SUTHERLANDSHIRE, county, northern Scotland, bound ed north and west by the Atlantic, east by Caithness, south east by the North Sea and south by the shire of Ross and Cro marty. Area, 1,297,914 acres (excluding water). The western and northern shores are indented with beautiful bays and sea lochs, and terminate at many points in precipices and rugged headlands. Almost the whole county is mountainous ; the summits are often of finer outline than those of the Grampian heights to the south, and the surface generally consists of wild desolate moorland. The highest point is Ben More in Assynt (3,273 ft.).
An irregular line from Loch Eriboll ,on the north coast to the neighbourhood of Cromalt near the southern boundary separates the two rock groups that form the foundation of the major portion of the county. On the western side of this line are ancient gneisses and schists (the Lewisian gneiss) ; these are penetrated by innumerable basic and acid dikes which generally have a north-west to south-east trend. On the eastern side of the line, occupying the whole of the remaining area except the eastern fringe of the county, is a younger series of metamorphic rocks, the Moine schists. In the north-west Torridonian breccias and sandstones rest unconformably on this gneiss, and Cambrian rocks upon the Torridonian ; the white Cambrian quartzite capping the dark Torridonian rocks on some of the hills forms a striking scenic feature. Granite masses appear in the eastern schists, and patches of Old Red Sandstone form high land near the south east coast. Evidence of glacial action is widespread.
The chief river is the Oykell, which, rising in Coniveall a peak of Ben More, flows south and then south-east for 33 m. to Dornoch Firth. Other rivers flowing to Dornoch Firth are the Helmsdale (22 m.), the Brora (28 m.), preserving in its name (bridge river) the fact that its bridge was once the only important one in the county; and the Fleet (i7), the estuary of which was embanked for i,000 yd. in 1813 by Thomas Telford, whereby rich
alluvial land was reclaimed. The Halladale (22), rising in Knock fin on the borders of Caithness enters the sea to the east of Port skerry. The district of Assynt is honeycombed with lakes and tarns, but the only large lake is Loch Assynt, 63 m. long, ft. above the sea. The ratio of the area of islands to the total area of the lake is greater than in any other British lake. There are many waterfalls; those of Escuallin, near the head of Glencoul, are among the finest in Great Britain.