﻿I860.] 



NICOl — N.W. HIGHLANDS. 



113 



there is no evidence to connect the great mass of crystalline schists 

 stretching from the north coast of Sutherland to the south of Inver- 

 ness-shire more closely with the mica-slates of Ben Hope than with 

 the gneiss of Seourie, Loch Inver, and the Gairloch, or to justify us 

 in throwing aside mineral characters for some assumed synchronism 

 in the age of the original, but now wholly altered, deposits. 



No such revolution in Scottish geology is, however, required. The 

 sections, when carefully examined, are clear and simple, and quite 

 analogous to those of other mountain-regions. Every fact and section 

 alleged in proof of the recent origin of the eastern crystalline strata 

 appears on investigation to lead directly to the reverse conclusion. 

 At Durine, the mica-slate of the Bishop's Castle, stated to overlie the 

 limestone, does not show a single calcareous bed in a thickness of 

 1000 to 2000 feet of strata ; and the same mica-slates are forced 

 up from below the limestone, by igneous action, in the very centre 

 of the field. At Whiten Head and Loch Emboli, the quartzites and 

 limestone, alleged to dip under the gneiss, are in part separated from 

 it by intrusive rocks, or meet it in wholly discordant position, often 

 so inverted and denuded that the upper limestone is entirely cut out 

 before reaching the line of supposed overlap. So too it is on Loch 

 More and Loch Glen Coul, where mere fragments of the quartzite 

 series are left abutting against, not dipping under, the old gneiss, or 

 separated from it by intrusive igneous rocks. In Assynt the so- 

 called " upper quartz-rock " is proved to have no existence, but to 

 be a mere upturn of the old quartzite, which is seen resting on the 

 gneiss for miles along its N.E. margin, and on the S.E. is divided 

 from it by a line of fault with huge intrusive masses of granite and 

 porphyry. Further south, in Cromarty- and Boss-shires, the same 

 phenomena prevail. The newer, overlying strata — whether the 

 limestone, the quartzite, or the Bed Sandstone — always overlie or 

 abut against, never dip under, the older eastern gneiss. In Skye, 

 finaUy, the Bed Sandstone, the oldest overlying deposit, dipping JST.W., 

 rests on the eastern gneiss dipping S.E., and thus in an entirely 

 discordant position. Such are the facts and sections on which I 

 have no hesitation in asking a verdict in favour of the old, long- 

 established principles of Scottish geology. 



VOL. XVII. — PAET I. 



