STRUCTURE OF THE ALPS. 383 



over very considerable spaces on the same side of the mountain 

 chain and are often found in the troughs separating parallel 

 groups, offers a strong argument in favour of the belief that 

 the process of upheaval, proceeded simultaneously, if not along 

 the entire line, at least over a very wide area." * 



And again he proceeds to point out 

 " When we find the same sedimentary rocks lying in the 

 same order and superposition on the outer slopes of the 

 parallel ridges, and in the trough between them (a relation 

 which holds good to a great extent in a section taken from 

 the Val Ferrex across the range of Mont Blanc and the 

 Aiguilles Rouges), we are entitled to infer the cotemporaneous 

 elevation of both ridges." f 



Dr. Ball then goes on to show that there are several 

 portions of the Alps where this same thing occurs, and 

 where a similar method of reasoning leads the mind 

 to a like conclusion, and he quotes a notable instance 

 where it is found that 



"the stratified rocks on the opposite sides of the 'Belledonne ' 

 group are so similar in their composition and arrangement, 

 as to lead to the inference that they must, at one period, 

 have formed portions of a continuous mass," 



indeed surveys in some cases seem to show that strata 

 thus divided by the extrusion of a mountain chain, 

 would fit back into their places almost exactly, if the 

 mountains were quietly lowered beneath the earth's 

 surface. 



We thus see that the vast preponderance of evidence 

 is all in favour of the hypothesis of the upheaval of 

 mountain ranges by matter forced up from below 



* The Alpine Guide (to Central Alps), by John Ball, F.R.S., page 

 xciii of Introduction. 



f Ibid., p. xciii of Introduction. 

 Ibid., p. xciii of Introduction. 



