﻿lii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I908, 



the Glarus away to the far Alps of Savoy one great continuous 

 overlapping sheet (nappe de r ecou vr em en t) of older rocks, which 

 has been pushed, as an immense canopy, over the younger forma- 

 tions, and has since been so deeply worn away by denudation that in 

 parts of its extent it has been reduced to mere scattered fragments.^ 



In the year 1884 Bertrand was selected as one of the French 

 mission which, under the directorship of Fouque, was sent to report 

 on the great earthquake in Andalusia. Together with M. Kilian, 

 he there studied the Secondary and Tertiary formations of the 

 provinces of Granada and Malaga. While still engaged in the 

 mapping of the French Jura, he had also assigned to him the 

 survey of some parts of Provence, especially the districts of Toulon 

 and Marseilles, and a portion of the districts represented on the Aix 

 and Draguignan sheets of the detailed map. It had been generally 

 taken for granted that this region of Southern France is one of 

 comparatively simple geological structure. Eut Bertrand, whose 

 eye was now trained to detect evidence of abnormal disturbance, 

 soon discovered that Provence, despite its likeness to an ordinary 

 plain, is in reality, as regards the disposition of its rocks, a portion 

 of the Alpine Chain, and forms a connecting-link between the Alps 

 and the Pyrenees. He found that its folds are horizontal (plis 

 couches), and that, although reduplicated upon themselves, the 

 strata retain or have regained a horizontal position. In the formation 

 of such plications, where the Trias, resting upon Cretaceous beds, 

 had been shifted for a distance of more than 6 kilometres, horizontal 

 displacements had played the chief part. In making known what 

 he regarded as the true structure of the ground, he boldly asserted 

 that how difficult soever it might be to conceive of vast flat folds of 

 sedimentary strata moving bodily over younger formations, as if 

 they had rolled onward like flows of basalt, yet theoretical 

 difficulties could not stand against the evidence of observed facts. ^ 



Besides these leading elements of structure, he detected in 

 Provence other features which he eventually recognized on a more 

 gigantic scale in the Alps. He was led also from these tectonic 

 studies to return once more to the consideration of the Franco- 

 Belgian Coal-field. He convinced himself that the structure of 

 what has been called ' the great fault ' of that region had been 

 misinterpreted, that all the phenomena there displayed point to a 



1 Bull. Soc. Geol. France, ser. 3, toI. xii (1884) p. 318. 



2 Ibid. vol. XV (1887; p. 667. 



