FKOM THE NORTH-WEST HIGHLANDS. 417 



resemblance to a true grit, T cannot help suspecting from others that 

 we have here only a very exceptional case of local crushing of a 

 Hebridean gneiss ; the difficulty is increased by the matrix in which 

 the fragments appear being darkened, in the case of the one which 

 is most grit-like, by an iron -oxide. 



87 (ibidem, p. 378). Seems to be a gneiss more or less crushed ; 

 parts of the slide are darkened as in the last ; and a good proportion of 

 the quartz has the aspect of being of secondary origin. 



88 (Camaal Loch, p. 378). This, again, is a most puzzling rock, 

 having a very clastic aspect ; but I have very strong suspicions that 

 it is only an exceptional specimen of one of the Hebridean gneisses 

 (containing two kinds of mica). 



89 (Calda Burn, p. 378), 90 (Dhuloch More Burn, p. 378). Though 

 these slides present some peculiarities and differences of structure, I 

 am disposed, though with hesitation, to place them in this group. 



91 (Calda Burn, p. 378) also belongs here. 



Rocks retaining traces of a Clastic Origin. 



The rocks hitherto described do not appear to include specimens of 

 the distinctly foliated gneisses and mica-schists, often garnetiferous, 

 which I have collected on Ben Pyn and received from other locali- 

 ties *, so that I pass on at once to a group most of which are evi- 

 dently formed of detritus obtained from the series just described. 

 Of these I shall not attempt to determine the definite geological 

 position. While all of them give marked indications of alteration, 

 this is insufficient to obscure the more conspicuous features of the 

 original structure. Representatives of this group have been de- 

 scribed by myself from the Torridon sandstone, quartzites, and 

 " upper gneiss " (from its northern escarpment), near Loch Maree 

 (Quart. Journ. Geol. Soc. vol. xxxvi. p. 98) ; so that it is needless 

 here to enter much upon details. 



92 (Dhuloch More Burn, pp. 361, 380.) Composed of subangular 

 fragments chiefly from the Hebridean series; probably Torridon 

 Sandstone. 



93 (ibidem, p. 380). "Fragments smaller and more angular. 



94 (Coniveall, pp. 360, 379, 383). Fragmental and variable in 

 structure from coarse to fine, derived mica, some fragments like bits 

 of a vein of quartz or a minute quartzite, some epidote. 



95 (Beolach Choinnich, p. 382) seems to be a rearranged Hebridean 

 rock. The fragments are mostly rather angular, among them many of 

 vein-quartz or the quartzose portion of a schist, felspar much de- 

 composed, a good deal of a secondary green mineral (? chlorite). 

 The rock appears to have been greatly compressed, as if nipped in a 

 fault. 



98 (Glen Coul, south side, p. 390). Chiefly quartz (fragmental) 

 and sericite (?), evidently much compressed, as shown by the flat- 

 tening-out of the grains. Probably not far in stratigraphic position 

 from the quartzite group ; perhaps rather above it. 



* These form the second group of the specimens which I have described in 

 an appendix to the paper by Dr. Hicks published in the present volume, p. 141. 



