Sept. 17, 1885 | 
NATURE 
473 
deposits of Silurian age will be found to be represented in a highly 
metamorphosed condition in our Scottish Highlands, remains to 
be discovered. There is such a perfect parallelism between the 
several members of the Silurian in Scania and in the Scottish 
Borderland, so well shown by the researches of Linnarson and 
Lapworth, that, as Nicol always anticipated, we may not im- 
probably find a portion of the rocks cf the Highlands to be 
altered forms of those of the Borderland. 
Since the last meeting of the British Association in the High- 
lands, much progress has been made in the study of that pre- 
eminently British formation—the Old Red Sandstone. Dr. 
Archibald Geikie has thrown much new light, by his valuable 
researches, on the relations of the several members of the vast 
series of deposits which go by that name ; while Dr. Traquair, 
bringing to bear on the subject great anatomical knowledge, has 
re-examined the collections of fossil-fish made by that indefatig- 
able explorer, Hugh Miller. The Old Red Sandstone is the 
only great system of strata which we possess, while it is either 
wholly absent, or very imperfectly represented, in Scandi- 
navia. 
In the year 1876, I was able to announce that a vestige—a 
small but highly interesting vestige—of the great Carboniferous 
system exists within the limits of the Scottish Highlands. Well 
do I recall the deep, the ineffaceable impression made upon my 
mind when, standing at the Innimore of Ardtornish, I beheld for 
the first time this relic of a great formation, preserved by such a 
wonderful series of accidents. What the inscribed stone of 
Rosetta or the papyri of Herculaneum are to the archzologist, 
this little patch of sandstone is to the geologist. Overwhelmed 
by successive lava-streams that were piled upon one another to 
the depth of many hundreds of feet, and then carried down by a 
fault which buried it at least two thousand feet in the bowels of 
the earth, this fragment has remained while every other trace of 
the formation has been swept from the Highlands by the besom 
of denudation. 
Highly interesting and important in these northern areas are 
the Mesozoic deposits, which in places attain a vertical thickness 
of several miles, and which must have originally covered.enormous 
tracts of country. Now, judged by that very fallacious test, the 
space which they cover upon our geological maps, they appear in 
the Scottish Highlands to be absolutely insignificant. 
The correspondence in characters between the several Second- 
ary formations on the two sides of the North Sea is of a most 
striking kind. I have had the good fortune to study the Second- 
ary rocks of Scania under the guidance and with the assistance 
of Professor Lundgren, of the University of Lund, who has made 
so many important discoveries in connection with them. While 
doing so, I have again and again felt almost constrained to pause 
and rub my eyes, to convince myself that I was not back again in 
Scotland—so complete is the correspondence between the mineral 
characters, the fossils, and the geognostic relations of these strata 
in the two areas. 
The Triassic rocks of Scandinavia, consisting of variegated 
sandstones and conglomerates, containing much calcareous ma- 
terial, are absolutely undistinguishable from those of the Western 
Highlands. In both countries the thickness of the deposits of 
this age varies within very short distances, their development 
being local and inconstant. The formation which in places 
exceeds a thousand feet in thickness, at other points is reduced 
to an insignificant band of conglomerate. On the eastern flank 
of our Highlands, yellow sandstones belonging to this formation 
have yielded to Mr. Duff, Dr. Gordon, Mr. Grant, and others 
that interesting series of reptilian remains which, in the hands of 
Professor Huxley, have been made to throw such important light 
on the forms of life which existed at that remote geological period. 
In the very similar deposits which occur in Scandinavia, however, 
reptilian remains have not as yet been obtained. The abundance 
and variety in form and size of the footprints which occur in our 
Scottish rocks of this age indicate the richness of the vertebrate 
fauna which must have existed at that distant epoch. 
On both sides of the North Sea, the Triassic rocks are found 
passing up insensibly into the great formation known as the 
Rheetic and {nfralias—a formation imperfectly represented in 
England and Central Europe by a few thin and insignificant 
Strata, but in our Highland districts attaining a vast thickness 
and exhibiting a magnificent development. This system of 
strata consists of alternation of marine and estuarine deposits, 
the latter containing in both areas thinseams of coal. In Scania, 
the working of the coal and fire-clays of these deposits has 
brought to ight vast numbers of fossil plants, which have been 
so well described by Nathorst. Several very distinet floras, 
occurring at different horizons, have been made out, and the 
relations of the beds containing these floras to one another, and 
to the marine strata with which they are intercalated, have been 
clearly demonstrated by the researches of Hébert, Erdmann, and 
Lundgren. That similar rich stores of fossil plants would reward 
a search as skilful and persevering as that made by our Scandi- 
navian brethren, if carried on in the equivalent strata of Scotland, 
there can be little doubt. 
The whole of the vast Jurassic system in these northern lati- 
tudes, attaining a thickness of 3,000 or 4,000 feet, appears to be 
similarly made up of alternations of marine and estuarine strata. 
‘lime would fail me to indicate even in the briefest manner the 
numerous problems of the highest interest suggested by the study 
of these vast deposits. At many different horizons, beds of coal 
anda the relics of a rich terrestrial vegetation abound. Most of 
these await careful study and description. So far as they are yet 
known, the Ferns, the Cycads, and the Conifers of the Jurassic 
rocks of the Highlands present wonderful resemblances with 
those described by Heer from strata of the same age in Norway, 
in Russia, in Siberia, and even far away in the Arctic regions. ‘lhe 
marine forms occurring in the associated strata seem to indicate 
that they belong to an ancient life-province, distinct from those 
in which the Jurassic rocks of Central and af Southern Europe 
were deposited. In the Upper Jurassic, so well represented in 
Sutherland by strata not less than 1,009 feet in thickness, we 
find evidence of the existence rof mighty rivers, the banks of 
which, though clothed with tree ferns, Cycads, and gigantic pines, 
yet at certain seasons must have borne down ice-buoyed blocks 
_of vast dimensions. 
That the succeeding Neocomian period was for Scandinavia 
and Scotland an epoch of elevation and of the prevalence of 
terrestrial conditions is indicated by the total absence of any 
trace of marine deposits of this age, no less than by the enormous 
denudation which can be shown to have followed the Jurassic 
and preceded the Cretaceous period. Our now ruined mountain- 
chain then probably formed the lofty watershed of a great con- 
tinent, through which flowed the mighty rivers that formed the 
deltas known as the English and German Wealdens. 
How powerful and prolonged were the agencies of sub-aérial 
waste during this period is shown by the fact that the relics of 
the Cretaceous formation are found resting in turn on every 
member of the Jurassic, the Rheetic, the Trias, and all the differ- 
ent Paleozoic and Archzean rocks. A great portion, indeed, of 
the thick and widespread Rheetic and Jurassic strata seems to 
have been removed by denudation before the commencement of 
the Cretaceous period. 
That thick strata of chalk once covered large areas of the Scott- 
ish Highlands and of Scandinayia we have the clearest proofs. 
In Scania and the adjoining parts of Denmark deposits of this 
age are found let down by tremendous faults, and these include 
eyen younger members of the series than are anywhere found in 
England. In the West of Scotland I have shown that thin de- 
posits of Cretaceous age, preserved to us by a wonderful series of 
accidents, still survive the tremendous denudation of the Tertiary 
periods. It is true that in Scandinavia and Scotland alike, the 
chalk alternates with sandstones and even with strata of estuarine 
origin, but the pure foraminiferal-rock that occurs in both areas 
could have been formed in no very shallow sea. That before the 
commencement of the great Tertiary denudation large areas, in 
Scandinavia and Scotland alike, must have been swathed in 
winding sheets of chalky rock there cannot be the smallest doubt. 
That considerable portions of these winding-sheets remained to 
so late a period as the glacial is shown by the fact that the in- 
destructible flints of the chalk with the rocks and fossils of the 
upper greensand abound in your boulder-clays of Aberdeenshire 
and Banffshire. 
Of the vast periods of the Tertiary we have left to us, either 
in the Highlands or Scandinavia, but few and insignificant relics 
in the form of stratified deposits. In our beautiful Western 
Isles and in Antrim the laya poured out in successive streams, 
during enormous periods of time, from the lofty volcanic cones 
of the earlier Tertiary epoch, has here and there buried patches 
of lake-mud, or river-gravel, or ancient soils. But everywhere, 
alike in the Highlands and in Scandinavia, we behold the most 
impressive evidences of the sub-aérial waste, and of the elevation 
that promoted this waste during the Tertiary epoch. Among 
such evidences we may reckon the circumstance that all traces 
of the vast deposits of the Secondary periods have been relent- 
lessly stripped away from the country, except where buried 
