SCENERY OF METAMORPHIC ROCKS. 387 



Scenery of Gneiss and Mica Schist. The mountains of this 

 system of rocks are formed into little groups separated by deep valleys 

 and long lakes, while their summits rise often more than 3000 feet 

 above the water. Their bases are usually and thickly covered with 

 birch underwood, and sometimes with forests of oak. Scenes of a 

 truly alpine character are very rare in Scotland, and perhaps nowhere 

 occur except in the Cuchullin mountains of Skye and the granite 

 peaks of Arran. The general outline of the mountains is pyramidal, 

 but this form, elegant at a distance, is broken on a near survey by 

 fantastic projections and bare cliffs and channels, which after storms 

 are changed into a multitude of waterfalls. The mountains of quartzite 

 and red sandstone rise abruptly from the great tableland of funda- 

 mental gneiss forming the lower hills on the West Coast of Scotland. 

 The greater elevations are smooth rounded cones, spire-like peaks, or 

 long serrated ridges, whose summits shine under the sun as though 

 capped with snow, and they send down streams of fragments to the 

 sea-lochs which wash their bases. The valleys which are destitute of 

 lakes are usually wild and barren and covered with scattered rocks. 

 Several of the most remarkable valleys in the Highlands follow the 

 strike of the strata ; as, for example, the extraordinary valley of lakes 

 united by the Caledonian Canal, whose highest point is but 90 

 feet above the sea. The valley of the Spey, Glen Tilt, Loch Tay, 

 Loch Long, Loch Fyne, Loch Awe, are other examples. The longi- 

 tudinal valleys are remarkably narrow, as if mere slits in the country, 

 while the numerous transverse valleys are in general more expanded. 



One of the most interesting valleys in Scotland is Glen Roy, which 

 branches off from Glen Spean in Lochaber. Narrow, parallel, con- 

 tiguous terraces, perfectly level as seen from a distance, and continu- 

 ous along the whole length of the glen, mark the higher part of its 

 bordering slopes with singular and most surprising terrace deposits 

 of boulder clay, often laminated and crumpled like the contorted drift 

 of Norfolk, the effect of ancient local operations of ice and level water. 

 It-has sometimes been conjectured that these terraces are traces of the 

 ancient margin of the sea, left uninjured during a subsequent elevation 

 of the whole country, to the extent, perhaps, of 1500 feet. But the 

 limitation of the terraces and the material of which they consist 

 rather suggest that the valley was dammed with a barrier of ice 

 which varied in level and held the waters in Glen Koy as a lake enclosed 

 by glaciers. 



As might be expected, the forms of the mountains, and especially 

 the shape of their summits, are often characteristic of the kind of rock 

 which constitutes them. Compare, for instance, the irregular head 

 and broken slopes of the Cobbler and other mountains of mica slate, 

 with the smoother sides and less angulated chloritic top of Ben 

 Lomond, and the conical summits of quartz rock on Benan, Sche- 

 hallion, and the Paps of Jura. 



Neither are the features of the valleys and waterfalls independent 

 of the nature of the rocks which they traverse. The unequal hard- 

 ness of mica slate, in particular, is often evident in the rapid streams 



