C— GEOLOGY. 65 



folding and the like. Tornebohm stands out the Giant of the North, of 

 such a stature that the generation that has succeeded him has been unable 

 to maintain his conquests. 



The interior of the Norwegian mountains must not delay us, \ntally 

 interesting though it be. We can only mention that a little west of 

 Jamtland lies the great Trondhjem field of folded early Palaeozoic rocks, 

 locally eighty miles broad. These rocks have yielded Ordovician and 

 Lower Silurian fossils, but differ profoundly in original characters from 

 the contemporaneous formations of the Jamtland foreland. They are 

 moreover in many instances highly metamorphic, with actinolite, garnet 

 and biotite. On this point there seems to be complete agreement among 

 Scandinavian geologists. In our own country there is a tendency to 

 associate the idea of metamorphic schists with a Precambrian date ; but 

 it should be remembered that in the Alps it is well established that 

 belemnites and other resistant Mesozoic fossils can be hammered out of 

 garnetiferous mica-schist. 



On returning to the North-west Highlands of Scotland, we arrive at the 

 opposite margin of the Caledonian Chain to that studied by Tornebohm in 

 Jamtland. A British audience knows full well the history of discovery in 

 this wonderful region. At an early date Murchison and Geikie recognised 

 schists as superimposed on the fossiliferous Durness succession and con- 

 sidered them to be a later conformable deposit, metamorphosed in situ. 

 Nicol, however, thought that a steep dislocation separated the two sets 

 of rocks. Callaway at last, in 1883, realised an ' overthrow ' locally 

 ' more than a mile in width,' while Lapworth in the same year published 

 his in many ways illuminating Secret of the Highlands. It is necessary, in 

 common justice, to recall that this paper was merely a preliminary account 

 and that subsequent exposition of his views was prevented by a breakdown 

 in health caused by the excitement of discovery. In 1884 Peach and 

 Home were able to show that the Moine Thrust-mass or ' Nappe ' has 

 travelled north-west through a minimum distance of ten miles. Their 

 report produced a profound impression, the more so because it was accom- 

 panied by a candid recantation on the part of Archibald Geikie, which 

 proved as helpful to tectonic science in 1884 as Heim's somewhat com- 

 parable letter on the Alps in 1902. 



Peach and Home, it may be added, worked in an atmosphere of 

 detachment. Most Alpine geologists of the day, Rothpletz excepted, had 

 rather exaggerated the idealisation of thrusts as vanished limbs of overfolds 

 — and in this respect they were followed by Lapworth. The generalisation 

 is undeniable ; but insistence upon it often leads to artificial presentations 

 of comparatively simple phenomena. Peach and Home merely reproduced 

 what they saw in Nature, and left it at that. Their lucid and beautifully 

 illustrated descriptions, dating from 1884, 1888, and 1907, have, in Suess' 

 words, ' rendered our northern mountains transparent.' 



The fossiliferous sediments of Durness, over which the Moine crystalline 

 schists are thmst, rest upon a flat-lying Precambrian sandstone formation 

 known as the Torridonian, and this in turn upon Lewisian Gneiss. The 

 Durness sediments are of Cambrian and probably Lower Ordovician age. 

 They are essentially a quartzite-limestone (largely dolomite) succession, 

 and in lithological character and fossil content they belong much more 

 1»2S P 



