1010 REPORT— 1885. 
conclusion, when we remember that a complicated series of fractures injected by the 
lavas of the Great ‘Tertiary voleanic foci of the West, extend right across the 
Highlands, the central valley, and the Borderlands of Scotland, and even traverse 
the whole series of the Secondary rocks in the North of Hngland. 
The indications of the tremendous manifestations of subterranean energy, to 
which these great dislocations owe their origin, are sometimes of a very striking 
kind. For hundreds of yards on either side of the faults, the two sets of strata 
are found bent and crumpled, and not unfrequently crushed into the finest dust 
(‘fault-rock’). In the case of the great Sutherland-fault, to which I have pre- 
viously alluded, we have a beautiful illustration of the way in which mineral veins 
may originate along such lines of fissure, for in the interstices of the granite of 
the Ord, where it has been broken up along this certainly post-Jurassic, and pro- 
bably Tertiary fault, fluor-spar and pyrites have been deposited in large quantities. 
It is impossible to study the tremendous movements and dislocations, and the 
enormous amount of denudation which have taken place in the Highlands and 
surrounding districts during Terdiary times, without being convinced that all the 
existing surface-features of the country must date from a comparatively recent 
eriod, The vast movements which have placed soft and hard masses in opposition 
along certain parallel lines—generally ranging in a north-east and south-west 
direction—and the denudation which has worn away the former, while it has left 
the latter standing in relief, must, I believe, both be referred to the Tertiary period ; 
though the disposition of rock-masses brought about by earlier movements would 
of course exercise a certain though subordinate influence in producing the existing 
forms of the surface of the country. 
At the close of the Jurassic period, and before the commencement of the 
Cretaceous, during the vast epoch marked by the deposition of the Neocomian of 
Southern Europe, a series of disturbances similar to those of the Tertiary, and 
scarcely inferior in their consequences, can be shown to have taken place. 
If the movements of the Scandinavian and Scottish rocl-masses, which took 
place in the Tertiary and Mesozoic periods respectively, were so startling in their 
magnitude and so vast in their effects, what shall we say concerning those far 
greater disturbances which affected the same area towards the close of the Older 
Paleozoic, and the keginning of the Newer Paleozoic, when this Northern Alps 
was still a living and growing mountain-chain ? 
These movements, in which both the Archzan and the Older-Paleeozoie rocks 
are found to be involved, have resulted in the production, through enormous lateral 
pressure, of those reversed faults, caused by the disruption along their axial planes 
of greatly inclined and compressed folds as so well described by Rogers. 
Dr. Archibald Geikie assures us that the studies of the geological surveyors 
in North-west Sutherland lead to the conclusion that certain masses of rock have 
thus been carried almost horizontally over others, along these ‘ thrust-planes ’ for a 
distance of at least ten miles. As the result of these tremendous lateral com- 
pressions, thin beds of limestone and quartzite, which have sufficiently definite 
characters to permit of their recognition, may be seen in Assynt, and in other parts 
of the Western Highlands, to be so repeated again and again by crumpline and 
faulting, that they have been regarded as deposits of enormous thickness; while, on 
the other hand, massive formations have been crushed and rolled out, thereby 
acquiring a laminated structure like so much pie-crust. Great portions of rock- 
masses, which, like the much-discussed ‘ Logan-rock,’ have been nipped between 
gigantic faults, show evidence under the microscope of having been crushed to 
powder and subsequently reconsolidated, while the surfaces of the ‘thrust-planes’ 
sometimes exhibit the phenomena known as ‘slickensides’ on the most gigantic 
scale. 
As we pass away from the central axis of this old mountain-chain, however, 
these complicated puckerings and dislocations pass gradually into more ordinary 
folds and faults, just as is the case with the Appalachians. The oft-repeated 
undulations of the Lower Paleozoic strata of the Borderland, so admirably 
described by Professor Lapworth, bear the same relation to the far more involved 
disturbances of rocks of the same age in the Highlands, which the foldings of the 
