TRANSACTIONS OF SECTION C. 1007 
On both sides of the North Sea, the Triassic rocks are found passing up in- 
sensibly into the great formation known as the Rhetic and Infralias—a formation 
imperfectly represented in England and Central Europe bya few thin and insignificant 
strata, but in our Highland districts attaining a vast thickness and exhibiting a mag- 
nificent development. This system of strata consists of alternation of marine and 
estuarine deposits, the latter containing in both areas thin seams of coal. In Scania, 
the working of the coal and fire-clays of these deposits has brought to light vast 
numbers of fossil plants, which have been so well described by Nathorst. Several 
very distinct 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 
lants would reward a search as skilful and persevering as that made by our 
candinavian 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 latitudes, attaining 
a thickness of 3,000 or 4,000 feet, appears to be similarly made up of alternations 
of marine and estuarine strata. Time 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 and the relics of a 
rich terrestrial vegetation abound. Most of these await careful study and descrip- 
tion. 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. The 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 of Southern Europe 
were deposited. In the Upper Jurassic, so well represented in Sutherland by 
strata not less than 1,000 feet in thickness, we find evidence of the existence of 
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 continent, through which flowed the mighty 
rivers that formed the deltas lnown as the English and German Wealdens. 
How powerful and prolonged were the agencies of sub-aerial 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 
different Palzeozoic and Archean 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 Scottish Highlands 
and of Scandinavia 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 even younger members of the series than are anywhere found 
in England. In the West of Scotland I have shown that thin deposits of Ore- 
taceous 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 indestructible flints of the chalk 
