OVERLYING ROCKS OF ROSS AND INVERNESS. 157 



igneous one, is fonnd on the Loch side of the road. The schists can 

 be traced along the road towards Banavie ; but before we reach the 

 latter place a granitic-looking rock is met with, which, however, shows 

 rather a gneissose appearance in places ; this is described in the Ap- 

 pendix, note 27. It has an old look, and if not of a gneissose cha- 

 racter, it must, I think, be an igneous rock of Pre- Cambrian age 

 which has suffered a considerable amount of crushing and some 

 change. In the area west of Glen Pinnan, as along the lines of 

 that district directly to the ST., the gneisses and schists are of the 

 true Ben-Pyn type. A collection of these may be examined in the 

 museum in Jermyn Street. Other specimens in that museum show 

 clearly that the old axis referred to above extends further south 

 than the neighbourhood of Loch Shiel, and that rocks of the (xlen- 

 Pinnan type are exposed at Strontian, almost directly to the south, 

 in Argyllshire. 



10. Conclusions. 



The facts derived from the careful examination of the various 

 sections referred to in this paper do not appear to me to lend sup- 

 port in any way to the view propounded by Murchison and Geikie 

 that the crystalline schists of their eastern areas repose conformably 

 upon unaltered rocks containing Lower Silurian fossils. The supposed 

 passage from unaltered to highly crystalline rocks has proved in 

 each case, on examination, to be a deceptive appearance due either 

 to a faulted junction or to some other accidental cause. The strati- 

 graphical evidence therefore on the strength of which the whole 

 theory depends for support fails entirely. To the east of Loch 

 Maree it has been shown that the fossiHferous sandstones are suc- 

 ceeded by flaggy beds at a low angle, which dip away from them to 

 the south-east. These flaggy rocks show, under the microscope, a 

 slight amount of alteration ; but the individual fragments out of 

 which they have been built up are always easily recognizable, and 

 there is no indication of that intimate crystallization of the felspar 

 and quartz which is so characteristic of the true schists. The flaggy 

 rocks meet the crystalline schists, which we recognize as belonging 

 to the Ben-Pyn type, quite abruptly along a line to the east, and 

 they are undoubtedly newer rocks than the latter. There is also 

 generally a marked discordance in the strike of the two groups. At 

 Achnashellach and Loch Doule, to the south of the lines last men- 

 tioned, the quartz rocks with Annelid-tubes abut against the same 

 crystalline schists of the Ben-Fyn type, the limestone and flaggy 

 series recognized in the other areas being entirely absent. Purther 

 south, however, near the head of Loch Carron, the limestone reposing 

 on quartz rocks with Annelid-tubes in abundance is brought against 

 the crystalline schists along its eastern margin by a fault. 



The eastward dip which prevails in the unaltered rocks aswell as in 

 the schists along this area has led to the belief that there was here a 

 conformable upward succession between the series. This appearance, 

 however, has been entirely produced by the fault ; and the apparent 

 conformability does not prove to be any thing like so marked as has 



