772 A TREATISE ON METAMORPHISM. 



during the transfer of the material. (4) As a result of the solution and 

 redeposition, energy is consumed. 



Therefore the energy required to accomplish granulation, on account of the 

 greater work of subdivision and the much greater ivork necessary to overcome 

 friction, is almost certainly greater than the energy required for recrystallization. 



If one premises that when the conditions are such that either granu- 

 lation or recrystallization might occur the process takes place which 

 requires the less expenditure of energy, this furnishes additional support 

 to the above conclusion; for wherever the conditions are such that recrys- 

 tallization can replace granulation, this occurs. 



In the artificial deformation of dry marble in the experiments per- 

 formed by Adams and Nicolson," the deformation was accomplished by 

 gliding and granulation. When the deformation was made in the pres- 

 ence of steam, the adjustment was, to a small extent, by recrystallization/' 

 (See pp. 747-748.) If the conditions could be so varied as to accomplish 

 the deformation by recrystallization mainly, it would be interesting and 

 important to compare the amount of work" done upon the mass during 

 deformation under these different conditions; for if this could be done it 

 would be possible, at least in this case, to make an estimate of the relative 

 energy demanded by deformation through granulation and through recrys- 

 , tallization. Doubtless this would be a difficult task. It would be necessary 

 to separate the total work done in the machine into the parts which were 

 required for the deformation of the rock mass and that required for the 

 deformation of the surrounding iron, and in one case also to estimate the 

 energy furnished by the water. If it were possible to make the determi- 

 nation, I anticipate from the analysis of the previous pages that the energy 

 required for deformation through recrystallization would be less than that 

 required for deformation through granulation. 



The question naturally arises, If less energy is required for reciystalli- 

 zation than for granulation, why did the latter process occur extensively 

 during mountain making in various regions! The answer is plain. Recrys- 

 tallization can not take place except where the proper conditions of temper- 

 ature and moisture are present. If the nucleus of the earth be shrinking, 

 the lithosphere must be reduced in size to accommodate itself to this nucleus. 



"Adams, F. D., and Nicolson, J. T., An experimental investigation into the flow of marble: 

 Philos. Trans. Royal. Soc. London, ser. a, vol. 195, 1901, pp. 376-382. 

 ''Adams and Nicolson, cit, pp. 382-385. 



