Scotland. 85 



proved by Professor Geikie, runs at the base of that 

 so-called chain right across Scotland, from the neigh- 

 bourhood of Stonehaven on the east coast, to Loch 

 Lomond on the west. Its effect is to throw down the 

 Old Eed Sandstone on the south-east, partly against 

 the Silurian rocks, and partly against volcanic tufas 

 and other strata belonging to the Old Ked Sandstone 

 itself. From that region, nearly the whole of the 

 Highlands, from the Grampians to the north coast of 

 Scotland consists of Lower Silurian rocks often intensely 

 contorted, and formed of quartz-rocks and flagstones, 

 gneissic and micaceous schists, clay slate, and chlorite 

 slate. Associated with these, there are certain lime- 

 stones, sometimes crystalline, but where less altered, 

 sometimes fossiliferous, fig. 55, p. 287. One of these, 

 near the base of the Silurian series, runs in a long band 

 from Loch Erriboll, on the north coast, southward to 

 Loch Broom, where for a space of about fifteen miles 

 it is lost, to reappear between the east side of Sleugach 

 and Loch Carron. The same limestone is well seen in 

 the Island of Lismore in Loch Linnhe, and here and 

 there on the sides of Strathmore or the Great Glen (a 

 line of fault), through which the Caledonian Canal was 

 constructed. Elsewhere in the Highlands, further east, 

 streaks of limestone occur. Immense masses of granite 

 here and there rise in the midst of the strata, one of the 

 smaller of which forms great part of Ben Nevis, the 

 highest mountain in Britain, 4,406 feet in height, and 

 another the splendid peaks of the Island of Arran. No 

 interbedded igneous rocks have yet been found among 

 the Silurian rocks of Scotland. 



The strata of the Highlands, not of Lower Silurian 

 age, are the Laurentian gneiss and Cambrian conglome- 

 rates and sandstones already mentioned, intersected by 



