Summary and conclusions. 135 



suppose the distance between C and D to be reduced. Then, in 

 the first place, we can only determine the change in distance, and 

 cannot say whether C has moved to the right or D to the left, except 

 by reference to some more distant point, such as the north pole, 

 which again can only be fixed by reference to some still more dis- 

 tant points such as the sun or stars, which obviously have nothing 

 to do with what goes on between C and D. Next, as regards this 

 tract, we may suppose the tract to be uniformly compressed, in 

 which case all the distances are proportionately reduced and the 

 positions of A and B relative to each other are unchanged ; or we 

 may suppose the distances from C to A and from D to B to remain 

 unchanged, those from C to B and from D to A being shortened, 

 and in this case the effect will have a different aspect according 

 as it is viewed from C or D. From the side of C it will seem that 

 A has been unmoved while B has been underthrust to the left, 

 but from the side of D the reverse action will seem to have taken 

 place, and A to have been overthrust to the right ; so far, how- 

 ever, as A and B are concerned it is only the relative movement 

 which comes into consideration, and the result in either case is the 

 same. From this we see that, as regards the processes which take 

 place within the hills themselves, the question of whether the sur- 

 face has been overthrust to the south or the lower layers under- 

 thrust to the north, is meaningless ; the form of the range, and of the 

 structures developed in the rocks of which it is composed, depends 

 on the power of resistance, and the direction in which yield- 

 ing takes place most easily, and not on the supposed direction 

 from which pressure is applied. In other words the form of the range 

 depends entirely on the distribution of resistances within the hills 

 themselves, and the answer to the question of the direction in which 

 this relief has taken place, depends entirely on the point of view 

 from which it is regarded. 



This matter has been dealt with as it seems important to clear 

 it up, for the fallacies referred to are widespread and deep-seated 

 and permeate a great deal of geological and other reasoning. The 

 whole of the arguments based upon them are meaningless, so far 

 as the origin of mountain ranges is concerned, but the fundamental 

 objections to Prof. Suess' theory are, that it fails to provide a 

 sufficient range of movement, and is incompatible with the existence 

 of compensation. The first of these objections can be put simply ; 

 given a solid, heated globe, cooling into space, it is possible to 



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