TRANSACTIONS OF SECTION C. 1009 
of the magnitude of these denudations become even more striking and impressive. 
Here we see, towering aloft, the ruined buttresses of vast rocky arches, that when 
complete must have risen miles above the present surface; there we find, lying 
side by side, rock-masses that could only have been brought together by displace- 
ments of tens of thousands of feet; yet so complete has been tbe planing down of 
the surface since, that it requires the most careful study even to detect the almost 
obliterated traces of these grand movements. The Alps and the Himalayas, during 
their elevation, have suffered enormous waste and denudation; but if the elevation 
were to cease and the waste to go on till these magnificent mountain-chains were 
reduced to masses of diminutive peaks, ranging from 2,000 to 8,000 feet in 
height, we should then have the counterpart of this stupendous ruin of the mountain- 
chain of the north. 
The history of the series of successive movements to which the rock-masses 
of our Highlands have been subjected is one well worthy of the most attentive 
study. When the evidence bearing upon the subject is carefully sifted and 
weighed, we become convinced of the fact that many of these movements—including 
some on a prodigious scale—must have taken place during what we are commonly 
accustomed to regard as comparatively recent geological periods. 
On the eastern coast of Sutherland, a mass of Secondary rocks, including 
several thousands of feet of Triassic, Rhietic, and Jurassic strata, has been let 
down by a gigantic fault, so as to be placed in juxtaposition with the Old Red 
Sandstone and the crystalline rocks. Now, taking the very lowest estimates of 
the thicknesses of the several strata affected, the vertical ‘throw’ of this fault 
must have exceeded a mile! It may not improbably, indeed, have heen at least 
double or treble that amount! Yet this great dislocation was certainly produced 
at a later date than the Upper-Jurassic period, for rocks of that age are found to 
be affected by it. 
Along the coasts of the Black Isle, strata of Middle and Upper Jurassic age 
are similarly found faulted against the ‘Old Red’ and the crystalline rocks. 
On ihe other side of the North Sea, in Ando, one of the Lofoten Isles, a patch 
of Lower-Oolite strata, consisting of marine and estuarine strata, and including 
beds of coal like that of Brora, is found let down by gigantic faults into the very 
heart of the crystalline rocks of the district. In Scania, the whole of the 
Secondary rock-masses owe their preservation in the same way to a plexus of 
tremendous faults, by which they have been entangled among the harder rocks. 
These faults have affected not only the Jurassic strata, but even the very youngest 
members of the Cretaceous series. 
Nor are we without evidence that some of the great faults are of post-Cre- 
taceous age, in this country, for in the Western Highlands displacements of several 
thousands of feet have been detected, which aflect not only the Upper Cretaceous, 
but also the Older Tertiary rocks. 
The effects produced by these great dislocations, which have a generally 
parallel direction in our Highlands, from north-east to south-west, are of the most 
startling character. Great strips of Triassic and Old-Red-Sandstone strata, like 
those of Elgin, and Turriff, and Tomintoul, and of the line of the Caledonian 
Canal, are found let down among the crystalline rocks by these gigantic faults. 
The great central valley of Scotland itself consists of masses of Newer Palso- 
zoic strata, faulted down between the harder Archean and Lower Paleozoic rocks 
which form the Highlands on the one hand, and the Borderland on the other. 
The evidences of the existence of these great faults were collected by many of 
the older Scottish geologists, like Landale, Bald, Chalmers, Milne-Home, and Nicol; 
and the accurate mapping of the country by the officers of the Geological Survey 
has, on the whole, tended to confirm their results. With regard to the age of these 
great dislocations of Central Scotland, it can only be certainly affirmed that they 
are of more recent date than the youngest Carboniferous strata; but I have long 
believed tbat, like many similar dislocations both in our own Highlands and in 
Scandinavia, they are really post-Cretaceous. 
Less difficulty perhaps will be found in accepting this apparently startling 
1885. 3T 
