On the Maintenance of Energy. 19 



connection with elevation and subsidence, and the formation 

 of mountain chains, ma}^ to a great extent, be explained in 

 this manner. Throuo-h extended observations of the I'ocks 

 in different formations and localities, it has been ascertained 

 by geologists that the subterranean forces are in a state of 

 continual flux over the surface of the globe. They make 

 themselves felt in an area, attain a maximum, and then 

 decline. As regards the formation of mountain chains — The 

 first stage appears to be the opening of a number of fissiures 

 running along a line near to that at which, in a long 

 subsecjuent period, the elevation of the mountain masses 

 takes place. The second stage consists in a general sinking 

 of the surface along the line of weakness and the deposition of 

 great quantities of sedimentaiy materials. The third consists 

 of a series of movements affecting the parts of the earth's crust 

 on either side of the line of weakness. By these movements 

 a series of tangential strains are produced, which result in 

 the violent up-crushing, folding, and crumpling of the 

 sedimentary materials deposited. Fissures again appear on 

 either side of the original line of weakness from which 

 volcanic outbursts take place. Mountain chains may be 

 regarded as cicatrised wounds in the earth's crust. The 

 subtei'ranean energies after probably accumulating for ages, 

 appear to first find an outlet. Enormous quantities of gases, 

 vapours, and molten rocks are brought to the surface. The 

 forces at last become exhausted and siibsidence takes place. 

 The original fissures become closed up and covered with 

 sedimentary deposits of immense thickness. The line of 

 weakness becomes stronger than the adjacent poi'tions of the 

 crust. After long ages the accumulated forces again make 

 themselves felt, elevation takes the place of subsidence, new 

 fissures are formed in the weakest places, the lateral forces 

 come into play, and the sediments overlying the original 

 fissure are upheaved. If we admit the existence of this 

 internal energy, we may have these processes repeated an 

 indefinite number of times over any portion of the earth's 

 crust. 



In this paper I do not propose to enter more fully into the 

 subject, but hope, at some future time, to have an opportunity 

 of exhaustively reviewing that branch of dynamical geology 

 which treats of it. I think that by means of this force, a 

 more or less complete explanation of the majority of the most 

 interesting problems presented can be given, especially as 

 regards the causes of the movements of portions of the 



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