﻿1861.] 



MtntCHISON AND GEIKIE- 



! HIGHLANDS. 



215 



interstratified through its mass. In its upper part it dips 12° S. of 

 W. at about 75° with a rude oblique cleavage. Eastwards the dip 

 changes to nearly S.W., and the angle varies from 50° to 70°. The 

 limestone, with slaty interstratifications, continues to occupy the 

 shore for at least half a mile, when it is underlain by another 

 series of slates and schistose beds towards the entrance into Glen Coe. 



Glen Coe. — As we ascend this glen the slates are succeeded by 

 quartzose rocks, and the whole valley is traversed by a network of 

 bands of porphyry. The, quartzose strata, however, appear to have a 

 decided westerly or north-westerly dip, which towards the entrance 

 of the Pass of Glen Coe becomes very gentle and then undulates 

 to the S.E. The amount of alteration now becomes very great. 

 Dykes and masses of felspathic porphyry abound, and it becomes 

 difficult to detect the actual bedding of the strata, which are split 

 vertically by a kind of jointing or rude cleavage. Towards the head 

 of the Pass the schists or slates are again met with, but in an in- 

 tensely altered condition, having passed into lydian-stone or jasper. 

 In spite of this metamorphism, however, we believed that they 

 showed a S.E. dip. Towards King's House masses of granite occur; 

 and the whole of this region, extending eastwards over the wild 

 moor of Pannoch and southwards among the mountains of Cruachan 

 Ben, is eminently metamorphic. 



The Breadalbane Forest. — The metamorphic region just alluded 

 to forms part of the great deer-forest of the Marquis of Breadal- 

 bane, and is a good centre from which to explore the geology of this 

 part of the Scottish Highlands. A reference to previous geological 

 maps will show that this extensive tract has been coloured as 

 " gneiss" with large areas of granite. In truth, however, the region, 

 is not one of true gneiss ; nor, so far as we observed, does the gra- 

 nite occur in the large, well-defined areas which have been assigned 

 to it. On the contrary, the same lower quartzose series and upper 

 schistose series form the groundwork here, as in such vast areas of 

 other parts of the Highlands, granite and porphyry occurring abun- 

 dantly in veins, knobs, hillocks, hills — in short, in every variety of 

 form and size, across the belt of country from Ben Cruachan to Loch 

 Pannoch. North-west of that belt, that is, along the Loch Leven 

 shores and towards Glen Coe, the order of succession is plain ; — 

 south-eastward through Glen Orchy and the surrounding country, 

 as we shall immediately see, the order is equally clear ; and even 

 in the granitified tract itself we are at no loss to determine along 

 what part of the great Lower Silurian series it lies. There is no 

 trace of any protrusion of the lower or Laurentian gneiss. The 

 stratified rocks indeed, as was pointed out to us on the spot by 

 the noble proprietor, are occasionally hornblendic ; but they cannot 

 properly be called gneiss, nor can they for an instant be mistaken 

 for the older gneiss of the North-western Highlands and Islands. 



The Moor of Pannoch* may be regarded as an undulating dome 



* Macculloch (Trans. G-eol. Soc, old ser., vol. iii. p. 129) describes the Moor 

 of Rannoch as a rugged plateau of granite, which extends to the head of Loch 

 Rannoch, or for twenty-four miles, and as "one of the most complicated and 



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