the Mountains of Scotland. 119 
Latitude has something to do with this. As is the case with the 
flora, with which its aspects are associated, so there is in the scenery 
a northern character which in many ways reminds one of the Alpine 
character. The impression produced corresponds no less with a 
geological truth: Scotland is one of the countries in which are to be 
found the best marked traces of those great movements of the earth’s 
crust by which mountains have been created. It is the witness of an 
ancient chain which ran on into Norway, of which the central core 
must have been located in the Grampian massif, and of which the 
shghtly diverging subordinate ranges were directed to the north- 
east, towards Edinburgh, and nearly to the north along the western 
coast, facing the Hebrides. This chain is doubly interesting, first 
because of its size and of the complex accidents which the work of 
the last ten years has made known within it, and also because of its 
great antiquity : the Caledonian Chain is one of the oldest, if not the 
oldest, which it is given us to reconstruct. One finds oneself there 
face to face with movements dating from the dawn of primary times, 
that is, from a time when theoretically! the mean thickness of the 
crust affected by these movements must have been sensibly less than 
at the time of the formation of the Alps. Was there in this an 
appreciable cause of difference in the behaviour of the phenomena ? 
What analogies as regards the whole and what modifications as to 
details will be brought out by a comparison with the Alps? No 
doubt the interpretation of these differences will always remain a 
little arbitrary ; but it is enough to indicate the question to which 
they may belong to show the interest which they possess. If it be 
added that the investigations carried out in the North of Scotland 
seem to be of a nature to throw some light on the still so obscure 
subject of the gneissose rocks, it will be seen that they are of an 
order far surpassing that of a mere regional description. They are, 
I think, among those that deserve to be presented in some detail 
to the readers of the “ Revue.” 
Thanks to a courteous invitation from Sir Archibald Geikie, 
Director-General of the Geological Survey of Great Britain, we 
were enabled, M. de Margerie and J, to study last summer the 
region of Assynt, under the guidance of Mr. Peach, who specially 
directs the work of the Scotch map.” Mr. Peach made us verify 
the principal sections published; we saw with him the irre- 
futable evidence on which they are based, and we admired the 
minute accuracy of the survey. Mr. Peach said to us at starting: 
J] do not think that there is now in the whole of Great Britain 
any region better or more completely known than that which we 
are about to visit.” We may add, after what we have seen, that in 
1 The theory of the cooling of the globe is not free from objections; it is 
necessary to admit that the earth is at the same time homogeneous, solid, and plastic. 
These are hypotheses which are certainly not all exact and that are admissible as 
approximations only. JI think, however, that the formule may be considered as 
indicating the drift of the phenomena. 
2 We had the good fortune of making this excursion in the company of Baron 
von Richthofen, the eminent Berlin professor, Professors Hughes and Sollas, and 
Messrs. Harker and Watts. 
