﻿1861.] MTTKCIHSON AND GEIKIE STRATA OF THE HIGHLANDS. 239 



affirm that it is most clearly a depositary rock, the lines of original 

 bedding of which coincide with the lines of ruetamorphism, since, 

 besides the alternation of variously coloured schistose layers, there 

 is really an intercalated bed of white quartzose and rounded pebbles, 

 thus clearly proving the whole to have been originally a mechanically 

 formed deposit. And, again, this one section in itself demonstrates 

 the utter disconnexion between such true stratification-planes and 

 cleavage ; for in advancing to the S.E. into the overlying deposit of 

 clay-slate, its layers {folia of Sharpe) are found to be traversed by a 

 real slaty cleavage of which there is not a trace in Ben Lomond. 



In fig. 4, where the section crosses Loch Tay, and where the dark 

 schists have no cleavage, Mr. Sharpe omits the great feature of the 

 case, the presence of those regularly bedded limestones which dip 

 under Ben Lawers : and, if he had taken time to examine the internal 

 structure of the country further to the he would have found 



other limestones reappearing together Avith the inferior quartz-rock 

 beyond Glen Lyon, in the Loch and Moor of Rannoch, thus forming 

 the other side of a great trough. 



His section across Glen Shee (fig. 5) is another indication of those 

 undulations of the upper schistose strata which we have observed. 

 In that tract we have already demonstrated that the contortions of 

 the original strata of black carbonaceous schist are traversed by lines 

 of parallel slaty cleavage*, thus showing even in a hand-specimen 

 the complete independence of cleavage from those lines in the cry- 

 stalline rocks which are true lines of bedding and are wholly uncon- 

 nected with slaty cleavage. 



When Mr. Sharpe affirms that the contortions of gneiss and mica- 

 schist " are far more complex than are ever found in the most dis- 

 turbed strata, and are such as could only be produced in matter in 

 at least a state of semi-fluidity," we refer the reader to the intensely 

 curved Carboniferous strata in Bride Bay, Devonshire, or to the num- 

 berless contortions of the Devonian rocks of the Rhine. In the 

 Silurian schists of the Lammermiiir Hills, and numberless " grau- 

 wacke" rocks in other tracts, both abroad and at home, multitudes 

 of similar rapid foliations have also been effected after the strata had 

 been accumulated, and probably before they underwent that change 

 by which they have passed into a highly crystalline state. 



Again, in tracing the folds of the different mineral masses through 

 the north of Scotland and in laying them down on maps, we have 

 convinced ourselves that the strata so reappear on various parallels 

 and so exhibit repetitions of the same geological relations to each 

 other, i. e. the quartz-rock and limestone occupying one zone, and 

 the mica-schists, the quasi-gneiss, and clay-slates another, that the 

 effort made by Mr. Sharpe to unite them in one crystalline mass, 

 which had been thrown into arches through the process of " foliation," 

 is, we conceive, antagonistic to the true principles of geological in- 

 ductive reasoning. 



Looking at these different mineral masses, whether as they succeed 

 to each other, or as they often gradually change their lithological 

 * Indicated also in Mr. Sharpe's fig. 5. 



