Sept. 18, 1885.] 



KNOV/LEDGE 



247 



treat, as belonging to the same geological district, both. 

 Scandinavia and Scotland. Not only is the succession 

 of geological deposits in the two areas almost completely 

 identical, but the characters of the several formations 

 and their relations to one another in the one country 

 are almost the exact counterpart of what they are in the 

 other. 



At the base, and forming the foundation of this 

 greatly-denuded mountain-chain, there exist enormous 

 masses of highly-foliated, crystalline ruckn. Tliese, in 

 great part at least, underlie the oldest known fossili- 

 ferous strata, and are, therefore, of jtro- Cambrian or 

 Archasan age. In spite of the labours of Kjerulf, Dahl, 

 Brogger, Reusch, Tornebohm, and many others in Scan- 

 dinavia, and of Macculloch, Nicol, and their successors 

 in this country, much still remains to be done in study- 

 ing the potrographical characters and the geognostic rela- 

 tions of these wide-spread formations. 



Although the bold generalisation which sought to 

 sweep all the crystalline rocks of our central Highlands 

 into the great Silurian net have admittedly broken down, 

 yet it by no means follows that the whole of these rock- 

 masses are of Archsean age. Nicol always held that 

 among the complicated foldings of the Highland rocks 

 many portions of the older Palasozoic formations, in a 

 highly-altered condition, were included. The same view 

 has been persistently maintained by Dr. Hicks, to whose 

 researches among the more ancient rock-masses of the 

 British Isles geologists are so greatly indebted, and 

 also by Professor Lapworth. To the settlement of this 

 very important question we may feel sure the effort of 

 the officers of the Geological Survey will be especially 

 directed. 



The geological surveyors of Scandinavia have been so 

 fortunate as to detect, in rocks of an extremely altered 

 character, a number of fossils sufficiently well preserved 

 for generic, and sometimes even for specific, identification. 

 Failing the occurrence of such a fortunate accident, I 

 confess that it has always appeared to me that the 

 disturbances to which these Highland rocks have been 

 subjected are so extreme, and the difficulty of making 

 out the original planes of bedding so great, that but little 

 can be hoped for from general sections constructed to 

 show the relations of the rocks of the Central and 

 Southern Grampians to the fossiliferous deposits of the 

 north-west of Sutherland. 



Since the last meeting of the British Association in 

 the Highlands, 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 

 ro-examined the collections of fossil fish made by that 

 indefatigable explorer, Hugh Miller. The old red sand- 

 stone is the only system (if strata which we possess, 

 while it is litlirr ^vIi.iHn absent or very imperfectly 





ed i, 



In the yviiv 1870 1 wa.. able to announce thatavcstige 

 — a small but highly interesting vestige — of the great 

 carboniferous system existed within the limits of the 

 Scottish Highlands. Overwhelmed by successive lava- 

 streams tliat wore jiiled npun one another to the depth 

 of many liuinlrcils cf fci •. uml (lien carried down by a 

 fault which l.url,,l ii ;,i Ir, -I -.(JUO ft. in the bowels of 

 the earth, this I'r.u-iiunt ii,:s iviaaiiu.l while every other 

 tr.ice of the formauon I,,,.-, been swept from the High- 

 lands by the besom of denudation. 



Down to post-glacial times Scotland and what were 

 now its outlying islands remained united with Scandi- 

 navia. I need not remind you how during the glacial 

 period they were the scene of a similar succession of 

 events, while from their tlun fr.r more elevated mountain- 

 summits struauis >■! ;jl:uii T ire flowed down and relieved 

 the mantle of sii'.v, v. Iii^li . nveloped them. But at a very- 

 recent geological 1 ( lii.il and indeed since the appearance 

 of man in this part of our globe — the separation of the 

 two areas, so long united, was brought about. 



In the district now constituting the North Sea, which 

 separates the two countries, great faults, originating in 

 the Tertiary eiwch, appear to have let down wide tracts 

 of the softer Secondary strata among the harder crystal- 

 line rock masses. The numerous changes of level, of 

 which we find such abundant evidence around the 

 shores of this sea, facilitated the wearing away of the 

 whole of these softer secondary deposits, except the slight 

 fringes that remained along the shores of Sutherland, 

 Ross, and Cromarty, on the one hand, and the isolated 

 patches forming Scania, Jutland, and the surrounding 

 islands on the other. Little could the Vikings, as they 

 sailed over this shallow sea, have imagined that their 

 predecessors in these regions were able to roam on foot 

 from Norroway to Suderey. 



It is almost impossible to over-estimate the effects 

 produced by the several denudations to which Scandinavia 

 and the Scottish Highlands have been successively sub- 

 jected. In that which occurred dui-ing the later Tertiary 

 periods, almost every portion of the non-crystalline rocks 

 that rose above the sea level was either entirely removed 

 or converted into level plains, which, covered with 

 drift deposits, now form districts like Scania and Den- 

 mark. Whereas in the great central valley of Scotland 

 hard volcanic masses are associated with the softer sedi- 

 mentary rocks, the former are left rising as picturesque 

 crags, standing boldly up above the general level, while 

 the latter are worn down and buried under drift. In 

 the west of Scotland a chain of volcanic mountains, with 

 summits towering to the height of from ten to fifteen 

 thousand feet, have been reduced by this same denudation 

 to basal wrecks, the highest portions of which attain to 

 but little more than 3,000 ft. above the sea level. 



During the great elevation and denudation which 

 marked the Neocomian period thousands of feet of strata 

 must have been removed over wide areas, as is proved 

 by the wonderful overlap of the cretaceous beds on all the 

 old strata. Of the enormous sub-aerial wa#te which went 

 on in these Northern Alps during the newer Pala30zoic 

 periods we have impressive evidence in the ^ast masses 

 of the old red sandstone and carboniferous rocks — them- 

 selves only a series of fragments that had survived the 

 later denudations—for these rnrks ^^,■v.■ Imilr nu of the 

 materials derivnl fm.n n„r.\-n!i. i-- \!' T' • T. .■■■M>ai 



sandstone is the nuinuiiinit :i:,'l ■ , ■ mi- 



meut too — of an.'i luT i'aul si ill .-. 1 .' I |-. us 



denudation. The thousands of feet oi o.nu.,.niLi-.,u- ..iid 

 sandstone of which it is made up consist of the dis- 

 integrated crystals of granites and gneisses that have been 

 swept away. 



Her 



- >.f 



vast rocky arches that xsluii c~^v.^l'\<u■ i ;;■ I, no risen 

 miles above the present surf:.. . ■. ili,r> ^^ . liiid lying 

 side by side rock masses that muia .-ul', hi . - 1 . vn brought 

 together by dispkicemeuts of tea., of ilu.u>.,nas of feet; 

 yet so complete has been the planing down of the surface 



