Ixxii rROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



south-eastern dip, resulting from the close oblique folds with steep or 

 inverted dips to the N.W. of each large anticlinal. He further re- 

 marks, that on approaching the northern side of the district the flex- 

 ures become progressively more open, and that the inequality in the 

 dip of the sides of the anticlinal diminishes, so that in this case also 

 the force would have been applied on the S.E. 



In the Jura Professor Rogers found the anticlinals to have one side 

 of the arch more incurved than the other, but not inverted ; and some 

 of them snapt near the point of most abrupt curvature. It is stated, 

 that wdiile the ridges are higher next the great plain of Switzerland, 

 all the individual flexures are steepest towards the Alps. The ave- 

 rage dip of the N.W. sides of the Jura anticlinals scarcely amounts to 

 40°, while on the S.W. it exceeds 70°. A great fault is supposed to 

 occur on the southern side of the Jura, arresting the expansion and 

 subsidence of the flexures in that direction. 



It is stated that in the Alps the axis-planes dip inwards from both 

 flanks towards the central portion, so that the masses are folded in 

 opposite directions ; the plications of the Bernese Oberland dipping 

 south,those of the chain of the St. Gothard and the Simplon toAvards 

 the north. In these mountains therefore the exertion of force would 

 be from the great central axis outwards towards the flanks on the 

 N.W. and S.E. 



Those familiar with the Alps must be well-aware of the great dis- 

 locations and folds exhibited, and of the whole presenting a crushed 

 appearance, such as we might expect from the heavy pressiu*e of the 

 masses composing them against each other on a line corresponding 

 with that of the main range. If the various dislocated parts were 

 reunited, and the folds flattened out, and the component beds restored 

 to the condition in which they were formed, the area now occupied by 

 the region of the Alps would have to be expanded to various distances 

 parallel to the main range, — the flanks pressed out into Italy on the 

 one hand, and towards the countries on the N.W. and W. on the 

 other. In looking at the flexures and dislocations in the Alps we 

 have to regard the mass of them, and in doing so we seem scarcely 

 to arrive at the conclusion that the flanks have been driven outwards 

 by impulses acting upon a fluid mass beneath in consequence of ten- 

 sion along the central axis ; but rather that the component beds were 

 squeezed from both sides up against a main central line, extending 

 along the main range of these mountains, so that the effects produced 

 upon the partly flexible and partly more unyielding rocks would 

 throw them into flexures and break them in directions, as if from a 

 force acting from the central portions outwards. The contorted, 

 broken and jammed masses would struggle to expand themselves, and 

 to avoid being squeezed and piled up into the atmosphere, would act 

 with all the power due to their gravity in forcing the rocks which 

 could yield into flexures, breaking others more rigid, and even the 

 flexures themselves when too sharp for the cohesion of the beds, so 

 that towards the central axis the anticlinals w^ould be sharper and 

 more folded, with inversions, and become less so towards the extreme 

 flanks. 



