4 Journal of Travel and Natural History 



Applecross, by Lochs Torridon, Maree, and Broom, through 

 Assynt to Cape Wrath. These sandstones pass underneath a 

 series of quartz-rocks and limestones, and these again dip 

 under a vast mass of overlying crystalline gneissose rocks 

 {c). It is this upper series which, as Sir Roderick Murchison 

 first pointed out, spreads out over all the rest of the Highlands 

 to the east and south. Its component strata, as roughly indicated 

 in the diagram, are crumpled and contorted, and come to the 

 surface again and again, being folded back upon each other, or 

 undulated into waves, so to speak, which rise and fall south-east- 

 ward to the Highland border. The reader will remember, how- 

 ever, that it is the convolutions in the strata themselves, which are 

 referred to, not the contour of the rocks upon the surface. Here 

 and there the place of the contorted masses is taken by granite, 

 porphyry, or other unstratified rock, but these interruptions may, 

 for our present purpose, be passed over. 



Along the southern edge of the Highland border, these hard 

 crystalline contorted strata sink under the softer rocks {d) of the 

 midland valley, on the further side of which there rises up into 

 the southern uplands another series {c) of hard contorted strata. 

 These are shewn by their fossils to belong to the same great 

 geological period as those of the Highlands (r). Indeed they 

 seem to be a prolongation of the same rocks, coming up again 

 from under the later formations of the Lowlands ; but in a less 

 crystalline or metamorphised form. They consist of bands of 

 various hard grits and shales which are thrown into endless 

 plications, the direction of the folds being, as in the Highlands, 

 from south-west to north-east. Occasional masses of granite, 

 porphyry, felstone, &c., occur among this group of rocks, and its 

 continuity is further interrupted by portions of the less antient 

 strata that creep up from the lower grounds on either side. But 

 the great bulk of these southern uplands consists of hard con- 

 voluted lower Silurian rocks. 



The midland valley is more complex in geological structure, 

 but our present object will be gained, if we bear in mind that 

 between the Highlands and the uplands of the south, the wide 

 intervening valley lies for the most part on comparatively soft sand- 

 tones, marls, shales, and other strata {d), belonging to the old red 

 sandstone and carboniferous formations, through which are distri- 

 buted masses of hard trap-rocks (/) that rise into more or less 

 conspicuous hills. 



