ENERGY REQUIRED FOR DEFORMATION. 771 



of the rocks, (2) that required for transfer of material, and (3) that required 

 to overcome friction. 



The energy factors in recrystallization are four in number: 



(1) Energy is continuously used in straining minerals during defor- 

 mation, but it is impossible to determine the amount of straining which 

 takes place, for evidence of the strain is continuously obliterated by 

 solution and deposition. If the mechanical stresses did not continuously 

 produce a state of strain, and thus disturb the equilibrium, it is probable 

 that the rate of the process of solution and deposition would be very slow. 

 It is this constant mechanical work in producing strain that keeps the 

 process of recrystallization g'oing. 



(2) Energy is required for the transfers of materials by solution. 



(3) Energy is required to overcome the viscosity of the solutions, or, 

 stated in a different way, energy is required to overcome the friction of the 

 molecules against the water during their movements. 



(4) As a result of solution and deposition in the lower zone, the 

 minerals produced are, on the average, more compact than before the 

 process. In so far as a more compact condition results energy is liberated. 

 On the other hand, the dominant chemical reactions of deoxidation, silica- 

 tion involving decarbonation, and dehydration all demand a large amount 

 of energy. The energy thus consumed is probably greater than that 

 liberated by condensation. It is therefore thought to be probable that the 

 process of solution and deposition consumes energy. In the rare cases in 

 which the minerals are equally compact before and after the process, and 

 no chemical change takes place, as in the recrystallization of a limestone, 

 the energy of solution and that of deposition balance. 



We may now compare the energy demanded for each of the different 

 factors in the two processes of granulation and recrystallization. The three 

 factors entering into gTanulation are paralleled by the first three of the four 

 factors mentioned below entering iiito recrystallization. (1) It appears 

 probable that the energy required to produce granulation is greater than 

 that required to produce a state of strain during recrystallization. (2) The 

 energy required for the actual transfer of the material by granulation and 

 by solution may be supposed to be the same. (3) The energy required 

 to overcome friction during- granulation is certainly vastly greater than the 

 energy required to overcome the friction of the molecules against the water 



