248 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 13, 



formable to the overlying limestones and talc schists. In proceeding, 

 however, to the opening from the glacier of Segnes, where the waters 

 issuing from a small lake or tarn, rush through crevices in the 

 secondary (Oxfordian) limestone, the very same masses of flysch 

 seem to dip under that limestone, which in its extension occupies the 

 striking ridges called the Flimser Stein, on the left bank of the Vorder 

 Rhein. Yet, these very same masses of Jurassic limestone, so in- 

 verted in the tract described, when followed to the heights south of 

 Pfeffers Baden, are found to plunge under the whole of the massive 

 limestones of neocomian and cretaceous age, and finally to be sur- 

 mounted by nummulite rocks and those grand masses of flysch from 

 which the mineral waters issue ; and thus, in proceeding towards the 

 lake of Wallenstadt, or towards the flank of the chain, all is symme- 

 trical and each rock resumes its normal position. AVliether therefore 

 I examined the pass of Martin' s-loch and its respective sides, and 

 looked at its absolute sections, or cast my eye to a distance over 

 the terraces of limestone surmounting flysch and nummulite rocks 

 as seen from its lofty summit, I was convinced that M. Escher was 

 correct in his delineation and mapping of the ground, although he 

 ingenuously urged me to try in every way to detect some error in his 

 views, so fully was he aware of the monstrosity of the apparent 

 inversion * . 



I dare not pretend to offer an explanation of the " modus operandi " 

 by which such a marvellous mutation of order has been produced 

 over so vast an area. I had indeed previously witnessed every pos- 

 sible contortion on a minor scale, and I might think it only necessary 

 to amplify the measure of such movements. But it became neces- 

 sary to admit, that the strata had been inverted, not by frequent 

 folds, as on the sides of the lake of Altorf or in the Hoher Sentis, 

 but in one enormous overthrow ; so that over the wide horizontal 

 area above-mentioned, the uppermost strata which might have been 

 lying in troughs or depressions due to some grand early plication, 

 were covered by the lateral extrusion over them of older and more 

 crystalline masses ; the latter having been forced from their central 

 position by a movement operating from centre to flanks, or in other 

 words, from the axial line of disturbance towards the sides of the 

 chain. One mference, indeed, seemed certain, that if the masses have 

 been thus inverted, there must have since occurred enormous denuda- 

 tions to leave the older limestone and talc schist merely as the narrow 

 cappings which they form on the summits of the ridges in the manner 

 represented in fig. 28. The grandeur of this phsenomenon may to 

 some extent be imagined by consulting that section ; but a true con- 

 ception of it can be alone formed by climbing over the ridges in which 

 the facts are laid bare, in one of the most pictorial regions of the Alps. 

 Not the least extraordinary feature of the phsenomenon is its appa- 

 rent uniformity, simplicity and grandeur, and the absence throughout 

 the tract of those mechanical plications, which, as we remove our ob- 



* The map and sections in which this startling phaenomenon is recorded, are 

 published in the work on the statistics of the Canton Glarus, by Professor Heer, 

 previously referred to. 



