﻿Vol. 66.~\ SCHISTS OF THE SCOTTISH HIGHLANDS. 589 



In the following year, however, Schardt [15], in his wonderful 

 interpretation of the pre-Alps, made it apparent that clean-cut 

 thrusts, similar to those of the North- West Highlands, play a very 

 important part in the tectonics of the Alps. Schardt's researches in 

 this connexion have furnished what is perhaps the most picturesque 

 development of modern tectonic theory. He has shown, in fact, 

 that the pre-Alps are a complex foreign mass of southern facies, 

 resting upon and folded with an autochthonous foundation of local 

 Helvetian character. Lugeon [16] in particular and many others, 

 including the veteran Heim, have been busy of late years extending 

 the scope of Alpine interpretation, and in their sections we may 

 recognize every connecting link between clean-cut thrusts of North- 

 AVest Highland type and others which merely modify, without 

 definitely replacing, the lower limbs of recumbent anticlines. 



But the convergence has not been all from the one side. The 

 Scottish Highlands, now that the schists have come to be minutely 

 studied, are yielding examples of recumbent folds which may well 

 be compared with those of the Alps. Mr. Clough [17] has suggested 

 the existence of flat folds with an amplitude of a mile and a half, 

 near Lochgoilhead, in the Cowal district of Argyllshire. He has 

 also discovered near Carrick Castle [18], farther to the south-east in 

 the same district, another important fold which probably belongs 

 to this category, although the sections do not suffice to indicate 

 its true proportions. A more extensively exposed example has;. 

 been described by Dr. Home [19] from the Fannich Forest in 

 Ross-shire, where a gently inclined core of gneiss of the Lewisian 

 type is overlain and underlain by sedimentary schists or gneisses 

 of the Moine type. The amplitude of the recumbent fold in this- 

 case is estimated at not less than 3 miles. Turning now to the 

 region at present under discussion, we find the first indication of 

 its complex structure in a description written by Mr. Maufe [20] 

 as a result of his work in 1905. ' The structure of the district,' he 

 says, referring to Glen Etive, * is evidently that of a huge overfold, 

 the limbs of which dip gently westwards and are at least 3 miles 

 in length (from trough to crest). The quartzite which caps the 

 hills, also forms the floors of the glens ' (cf. Section H, PI. XLIY). 

 My own work, which has been dependent at all stages upon the 

 cordial co-operation of my colleagues, has extended Mr. Maufe's 

 results : it has shown that structurally the whole district is an 

 assemblage of recumbent folds, broken and entire, in certain cases 

 not less than 12 miles in amplitude ; and that these folds are by 

 no means always in the position in which they were formed, since 

 many of them have been subsequently rucked up and bodily 

 involved in other isoclinal folds, which, though of minor importance, 

 are still of considerable amplitude [21]. The fold-faults which 

 accompany these recumbent folds, where the latter are broken, are 

 not confined to the lower limbs of anticlines. This is a peculiar 

 feature, which may have a considerable bearing upon the tectonic 

 problems presented by crystalline schists in other regions besides 

 Scotland. 



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