the Mountains of Scotland. 17 
friction breccia several metres thick in which the broken fragments 
are visible to the naked eye, but which is divided into parallel layers 
and appears stratified. The bedding is here evidently mechanical ; 
it is a cleavage of the broken mass. “For Mr. Peach the phenomenon 
is the same when the fragments cease to be visible and when they 
melt into an entirely crystalline paste. Hverything then, the 
texture of the rock, as well as the appearance of sedimentation or 
its crystalline structure, would be the result of mechanical action, 
and that over an area of some thousands of square kilometres. It 
would even not be necessary to regard this enormous mass of schists 
as corresponding to any particular stage; the materials of which it 
consists would be furnished pell-mell by the rocks and deposits 
anterior to the movements. Here the hypothesis becomes some- 
what too colossal to enable one to associate oneself with it. It 
seems to me difficult not to see in these crystalline schists as a whole, 
one special formation of definite age, which if not yet determined 
is certainly anterior to the Cambrian, a true stage (étage) in the 
ordinary acceptation of the term, and more or less to be likened to 
the micaceous schists and slates (phyllades) which in France form 
the top of the crystallophyllian series. It may be admitted that the 
apparent thickness of this group is augmented by a series of thrust 
planes and by the mechanical piling up already described ; it may 
also be admitted that the visible bedding is cleavage. But in the 
absence of new arguments one can scarcely go further; the still 
recognizable patches of ancient gneisses or of Silurian beds found 
within the mass, must be considered as more ancient or more recent 
parts brought in by folds or by faults; but they cannot bear out the 
conclusion that the whole mass was formed of the same materials. 
As to the sudden appearance of a thick sedimentary series entirely 
wanting a few kilometres to the west, it reminds one exactly of 
what takes place in the Alps in the zone between the massifs 
of Mont Blanc and Monte Rosa. It would even be possible to 
follow, member by member, a curious correspondence in position 
between the series of the two regions: the gneisses of the Mont 
Blane chain would tally with those of the Scottish coast; on these 
gneisses rest unconformably on the one hand the Carboniferous 
deposits, on the other the Torridon Sandstones of which I shall speak 
presently ; the quartzites and limestones of the Trias take the place 
of the Cambrian quartzites and limestones of Scotland, and, east of 
the last named, instead of seeing a reappearance of the older divisions 
over which they lie to the west, we encounter only an immense suc- 
cession of schists unknown on the other side, the Moine schists in 
Scotland and the lustrous schists in the Alps. In these last, more- 
over, patches of Trias are found intercalated, as shreds of Cambrian 
are enclosed in the schists of Scotland. 
This is, however, not the place to insist upon these Moine Schists, 
the question which of all others remains the most obscure, and on 
which next to nothing has been published. The last observations 
I wish to mention in concluding are those relating to the gneiss 
rocks of the coast. There the post-Cambrian movements are no 
longer felt ; the prodigiously dislocated region which we have been 
