Sept. 10, 1885 | 
NATURE 
497) 
thickness. Resemblances in mineral character have been proved 
not only to have been, at their best, very unsafe guides indeed, 
but to have actually betrayed those who trusted in them into the 
most serious errors. But for the discoveries of Charles Peach 
on the one hand, and of Patrick Duff and Dr. Gordon on the 
other, geologists would probably still continue to class the sand- 
stones of Torridon and Elgin respectively with the ‘‘ Old 
Red.” 
But perhaps the consideration of greatest importance which 
is impressed upon us by this retrospect is, that in these High- 
land districts we must be always prepared to meet with rock- 
masses of very different geological ages, thrown into puzzling 
juxtaposition by the gigantic movements to which this part of 
the earth’s crust has been subjected. He who enters on the 
study of Highland geology without being prepared to encounter 
at every step complicated foldings, vast dislocations, and stupen- 
dous inversions of the strata, can scarcely fail to be betrayed 
into the most disastrous and fatal errors. 
The early history of Scotland is inextricably interwoven with 
that of Scandinavia. ‘This proposition, true as it is of the in- 
significant periods of which human history takes cognizance, 
applies with even greater force to the vast epochs that fall within 
the ken of the geologist. To us the separation of Scotland and 
Scandinavia is an event of very recent date indeed; it is not 
only an accident, but an uncompleted accident! The Scottish 
Highlands, with the Hebrides and Donegal on the one hand, 
with Orkney and Shetland on the other, must be regarded—to 
use a technical phrase—as mere “‘ outliers” of the Scandinavian 
Peninsula. 
We must acknowledge, at the outset, that the study of the 
geological history of this Scandinavian peninsula and its outliers 
is a task bristling with difficulties. The problems presented to 
us in our Scottish Highlands are vast, complicated, and at times 
seemingly insoluble. But they are precisely the same problems 
that confront our brother geologists in Scandinavia. And if our 
tasks, our doubts, our perplexities are the same, we equally 
“share in the advantages and triumphs of discovery. 
The geologists of Scandinavia—and right worthy sons of 
Thor they are—have the advantage of possessing a territory 
almost limitless in its vastness, and seemingly infinite in its 
variety. But the very extent of their splendid country, with its 
sparse population and restricted means of communication, in- 
creases the difficulties of their task. ‘The harvest truly is 
plenteous, but the labourers are few!” With our smaller area, 
if we cannot expect so much variety, we may hope to gain some- 
thing from the number of our students and the greater access- 
ibility of our fields of labour. 
Nor would I undervalue, in this connection, the importance 
of the union of this country with England. I allude, of course, 
not to events of yesterday, like the Accession of James VI. to 
the English throne and the Parliamentary Act of Union, but to 
operations that preceded these by many millions of years! It 
is no small advantage that a country like Scotland, in which the 
rock-formations are found hopelessly crushed and crumpled 
together, or broken into a thousand illfitting fragments that seem 
to defy all attempts to reduce them to order, should be united to 
one like England, where, by comparison, all is orderly and 
simple, the strata lying in regular sequence like well-arranged 
volumes in a library, and only await the touch of the geologist’s 
hammer to display the wealth of their fossil contents. 
The great Scandinavian massz/, with its outlying fragments, 
constitutes the ‘“‘ basal-wreck ”—to employ Darwin’s expressive 
term—of a great Alpine chain. On other occasions I have 
endeavoured to show how much our study of the nature and 
products of volcanic action is facilitated by the existence of 
similar ‘‘ basal-wrecks””’ of volcanic mountains, like those which 
exist in your beautiful Western Isles. In the same way, I 
believe we may learn more by the study of this dissected moun- 
tain-chain, concerning the operations by which these grand 
features of our globe have originated, than by the most pra- 
longed examination of the superficial characters of the Alps or 
the Himalayas. 
Here the scalpel of denudation has laid bare the innermost 
recesses of the mountain-masses, and what we can only guess at 
in the Alps and the Himalayas, here stands in our own High- 
lands clearly revealed to view. 
It is a well ascertained fact that all the existing lofty moun- 
tain-chains have been formed at a very recent geological period. 
The reason of this it is not difficult to divine. In the higher 
regions of the atmosphere, the forces of denudation work so 
rapidly that within a very short period—geologically speaking— 
the vastest mountain-chain is razed to its very foundations— 
“They melt like mists, the solid lands, 
Like clouds they shape themselves, and go!” 
It is not surprising then to find Powell and Gilbert, fresh from 
the study of the grand mountain-masses of the American Con- 
tinent, giving expression to these thoughts in the following 
words: ‘* All large mountains are young mountains, and, from 
the point of view of the uniformitarian, it is equally evident that 
all large mountains must be growing mountains ; for if the pro- 
cess of growth is continuous, and if a high mountain melts with 
exceptional rapidity before the play of the elements, it is illogical 
to suppose that the uprising of any mountain, which to-day is 
lofty, has to-day ceased.” 
The Scandinavian Alps w2rea living and a growing mountain- 
chain in the far distant Palaeozoic period. Now it is not only 
dead, but stretched on the dissecting table of the geologist—its 
outer integuments and softer tissues stripped away, and its very 
skeleton bared to our view—a splendid ‘‘ subject” for the student 
of mountain anatomy. 
One of the first to recognise this value of our Scottish High- 
lands to the student of Orographic Geology was the late Daniel 
Sharpe. He had made himself familiar with many of the 
characteristic details of Alpine architecture—so far as it was 
then understood—and was able to show that the foliated masses 
of our Highland districts exhibit precisely those relations which 
would be seen if the contorted and fan-like masses of the Alps 
were planed away by denudation. Nor in suggestions of this 
kind, as we have seen, was James Nicol far behind Sharpe ; 
but at that time many of the most important features of moun- 
tain-structure were unrecognised or misinterpreted, and the con- 
clusions of these geological pioneers were little more than 
guesses—though very valuable and suggestive guesses—after 
truth. 
It is to our geological brethren over the Atlantic that we are 
especially indebted, not only for many important discoveries in 
the mechanics of mountain-formation, but for clearing away 
many of the clouds of error in which the subject had become in- 
volved. To Henry Darwin Rogers, who, after a career of 
valuable geological work in his native State of Pennsylvania, 
accepted the hospitality of this country, and spent the last decade 
of his useful life as Professor of Natural History and Geology in 
the sister university of Glasgow, must be assigned the foremost 
place in that school of orographic geologists which has grown up 
in America. 
The first sketch of the important theory of mountain-building 
to which Rogers and his fellow-geologists were led by the study 
of the Appalachian chain, was published in 1842, but it was not 
till 1858 that the complete evidence on which this theory was 
founded could be published. 
The conclusion at which Rogers arrived was, briefly expressed, 
as follows :—The Appalachian mountains were carved by denu- 
dation out of an enormously thick mass of stratified deposits, 
thrown into a series of parallel wave-like folds. To the west- 
ward of the mountain range ‘‘ the crust-waves flatten out, recede 
from one another, and vanish into general horizontality ; ”’ but 
towards the heart of the mountain-mass the same flexed strata 
become greatly crowded together, their ‘‘ axis-planes,” become 
more and more inclined, till at last their folds, yielding at their 
apices to the tremendous lateral thrust, fractures twenty to 
eighty miles in length, and attended with a displacement of 
20,000 feet or more, were produced. 
Unfortunately Rogers accompanied these just views of moun- 
tain structure with certain crude speculations and untenable 
hypotheses concerning the methods by which they were produced. 
But in the minds of other American geologists, among whom 
may especially be mentioned Dana, Le Conte, and Vose—the 
fruitful ideas of Rogers have undergone development and ex- 
pansion, while they have received abundant illustration through 
the labours of that active band of pioneers—the United States 
Geological Survey—including Clarence King, Powell, Emmons, 
Hague, Dutton, Gilbert, and many others. 
Nor have the brilliant results attained by these investigators in 
the New World been without their effect on the geologists of 
Europe. Lory, Suess, Heim, Baltzer, and others have shown 
that the clue to the right understanding of the structure of the 
Alps, which had been so diligently sought and so long missed by 
Von Buch and De Beaumont, by Studer and Favre, was now 
