Van Hise — Metamorphism of jRocJcs and Rock Floivage. 87 



the experiment at about the same speed as during its earlier 

 stages, for L3 : ±2 about as 18 : 60. 



During the experiment, unless hydrous minerals were pro- 

 duced, the water remained a constant quantity, and continued 

 work. This could have been continued so long as the temper- 

 ature and pressure were sufficient and glass was available for 

 crystallization through solution, as a result of which the 

 material is condensed. If no hydrated minerals are formed, 

 there is no reason why a small amount of water cannot con- 

 tinue the process indefinitely. 



If in this experiment we suppose the condensation of recrys- 

 tallization to be 10 per cent, the amount of condensation in 

 diabase in passing from the glassy to the crystalline condition, 

 as shown by Barns, this would mean (neglecting the condensa- 

 tion of the water) that in one hour, in order to have given an 

 apparent volume contraction of 18 per cent, the water had dis- 

 solved 1*8 times its own volume of the glass, and deposited crys- 

 tallized material with 10 per cent less volume. Therefore, 

 for the water to dissolve a volume of glass equal to that of the 

 water and deposit it in a crystallized form would require SSI- 

 minutes, or approximately one-half hour. 



During the process of deformation of the rocks the material, 

 if not dissolved, may be strained even to the point of granu- 

 lation by the mechanical processes ; also so far as strain occurs, 

 or the particles are small, the minerals are in a state in which 

 solution is easier than for unstrained or larger mineral par- 

 ticles. However, it is probable that the solution of such 

 mineral particles and the deposition of the material in an 

 unstrained crystallized condition is considerably slower than 

 that of amorphous glass, for it cannot be supposed that the 

 same amount of energy is potentialized in the mineral particles 

 as in the glass. But the further the strain goes before fracture 

 the more energy is potentialized, or if fractures occur smaller 

 particles are produced. Moreover, the contained water is in 

 small capillary or subcapillary spaces, and therefore a given 

 volume is acting upon a much larger surface than in the 

 capillary tubes used by Barns in his experiments. In so far as 

 granulation occurs, the surface for action is still further in- 

 creased. All these conditions are favorable to solution and re- 

 deposition ; therefore the greater the straining and resultant 

 granulation, the more rapid the process of recrystallization ; 

 hence in the deep-seated zone mechanical disintegration never 

 gets far in advance of solution and redeposition. 



If it be supposed in the capillary and subcapillary spaces 

 within the rocks that the speed of solution of minerals is *1 of 

 that of glass, water would dissolve its own volume of minerals 

 and redeposit the material in about five hours. If the deep- 

 seated rocks be supposed to contain 2 per cent of water by 



