Pre-Cambrian Rocks of Ross-shire. 157 
N.W. strike is clearly maintained.” The persistency of a N.W. 
strike in the Pre-Cambrian rocks at Gaerloch, Torridon and Loch 
Maree is undoubtedly a fact of great importance, and must not be lost 
sight of in any examination carried into the adjoining areas ; and if 
such a strike is found in any of these in association with the 
only other evidence referred to in the above remarks, viz. an 
identity in lithological composition, the evidence of correlation 
in the rocks belonging to those areas must be considered con- 
clusive as far as these authors are concerned. Indeed, most 
geologists who have had much experience amongst the older 
rocks, and who have been able to realize thereby the prevail- 
ing influences, physical and chemical, to which they have been sub- 
jected, cannot fail to arrive at some such conclusion. The Pre-Cam- 
brian rocks along both sides towards the eastern end of Loch Maree, 
as at Gaerloch and Torridon, are covered by Cambrian conglomerates 
(or breccias) and sandstones, derived as there from the immediately 
underlying rocks. They rest horizontally, or with a very slight in- 
clination to the 8.E., on the upturned edges of the older rocks, and 
fill up the unevennesses of the surface frequently recognizable on 
the old Pre-Cambrian floor. This floor it is clear remains much as 
it was when the overlying rocks were deposited upon it, and its 
subsequent elevation must have been produced without materially 
altering the configuration of its surface. It has of course been fractured 
at many points, and consequently dragged down with it at these 
places the overlying rocks. In its then crystalline (metamorphosed) 
state it could not bend nor yield in any other way than by fracturing, 
and it behoves us not to forget this in our inquiries, for it 
offers the clue by which we may judge as to what physical changes 
these rocks could possibly have been subjected to since.! The floor 
and the overlying rocks are dropped to a lower horizon on the south 
side of the lake than on the north, by the fault which runs through 
and parallel with the lake. This fault, however, is a mere down- 
throw to the §.W., and has not in any way interfered with the strike 
either of the lower or with that of the overlying beds. Indeed, all 
their distinctive characters, and their relations to one another, are 
exactly the same on both sides of the fault. I call especial attention 
to this fact (it is referred to also by Murchison and Geikie)’; for the 
interpretation here of the effect produced by this fault does not 
commend itself to some when applied to one part (Glen Docherty) 
along its course, where the results and the appearances generally 
seem to be identical with those observed here and throughout at 
many other points. 
There are some apparently who would rather believe in the 
possibility of twisting a large portion of the old metamorphosed 
floor, with its superincumbent weight, at right-angles for several 
miles to that from which it has been detached, without greatly 
1 Rather too much of the floor is left uncovered in the map to the north of Ben 
Larig. The exposures are chiefly here along lines of valleys and the borders of 
lakes. 3 
2 Quart. Journ, Geol. Soc. vol. xvii. p. 190. 
