122 Notices of Memoirs—Prof. M. Bertrand— 
remain associated with one of the most brilliant phases of Scottish: 
geology. 
IJ. The share of those who have followed Professor Lapworth is 
sufficiently handsome to enable me, without depreciating their merits, 
to insist upon those of him who was the precursor. The earlier 
work had shown general affinity to Alpine structure. That of 
Messrs. Peach and Horne, whilst adding precision to the resemblance, 
at the same time has brought out differences of which the interest 
is considerable. 
The Geological Survey, although rather prejudiced in favour of the 
old views, hastened to undertake the general study of the region 
where the phenomena pointed out by Professor Lapworth could be 
verified and followed out. Already, in 1884, Mr. Peach, placed in 
charge of these investigations, was able to invite the Director-General 
to come and ratify the decisive results which had been obtained, and 
Sir Archibald Geikie, abandoning the opinion he had hitherto held, 
lost no time in accepting the evidence of the facts, and in widely 
announcing the change of view by publishing in ‘ Nature’! the 
-conclusions to which the officers of the Survey had been led, step 
by step, and almost in spite of themselves. But it was only in, 
1888 that a detailed report was issued embracing the whole of the 
observations made by Messrs. Peach, Horne, Gunn, Clough, Hinxman, 
and Cadell.? Since then, the observations have been completed, but 
the Report of 1888 still represents the principal features of the 
results obtained. 
These results are remarkable for more reasons than one. On 
hearing that the mountains of Scotland showed traces of horizontal 
displacements comparable to those of more recent mountain ranges, 
it was possible to suppose that the ancient chain would prove to be 
constructed on exactly the same plan as the’Alps. Later, on finding 
in the sections of Messrs. Peach and Horne important differences 
between them and the classical types of Switzerland, it was still 
possible to believe that these differences might be more apparent 
than real, and that by varying the method of interpretation they 
might be reconciled. All such expectation must, I think, be given 
up; the differences are real and profound; their causes and their 
theoretical importance can be discussed, but their existence cannot 
be contested. 
To begin with, there are three great planes—or better, three great 
independent surfaces of “push” or carriage (thrust planes). Hach 
of these has produced horizontal displacemeuts of several kilometres. 
For the third, the most easterly, these displacements attain 15 
kilometres. The first two have brought into superposition above 
the normal series only beds similar to those which they overlie ; 
the third, on the contrary, has brought a different series into 
superposition—precisely that of the ancient ‘‘recent gneisses” of 
Murchison. In places, the last thrust plane comes to override the 
first two; so that there is then a three-storied edifice, the two lower 
1 « Nature,’’ 13th November, 1884. 
2 Quart. Journ. Geol. Soc. 1888, p. 378. 
a om 
