RELATIONS OF GRANULATION AND RECRYSTALLIZATION. 739 



various localities interstratified with these are coarse marbles with granolitic 

 textures showing no other strain effects than those of polysynthetic twinning 

 and similar phenomena, which may have been developed by the slight 

 stresses to which the material was subjected in section cutting in the 

 laboratory. 



The coarser the particles the more likely is granulation to be of 

 importance. The finer the particles the more likely is recrystallization to 

 be dominant. The finer the particles originally or by granulation the 

 greater is the surface exposed to the action of the solutions. The dissolving 

 power of water, when not nearly saturated, is almost directly in proportion 

 to the area upon which it can act. If the grains of a rock be broken by 

 granulation into particles having radii 0.1 of those of the original grains, 

 each small grain will have 0.001 the volume of an original grain, and the 

 total surfaces of the fewer original grains will be to the total surfaces of 

 the more numerous grains as 1 : 10. If the granulation goes so far as to 

 give the granules radii averaging only 0.01 of those of the original grains, 

 each small grain will have 0.000001 of the volume of the original grains, 

 and the total surfaces of the original grains will be to the total surfaces Of 

 the granules as 1 : 100. A good illustration of mechanical granulation is 

 furnished by the anorthosites described by Adams." Mr. S. H. Ball has 

 compared the size of the grains of the original anorthosite and the granu- 

 lated anorthosite in two specimens, the result showing that, on the average, 

 the ratio of the diameters of the feldspar grains of the original rock to 

 the diameter of the granulated grains is 1 : 40, or one feldspar grain of the 

 original rock is broken into about 64,000 grains. 



Ultimately, even under conditions otherwise favorable to granulation, 

 finer subdivision does not continue, for so large a surface is exposed to the 

 action of the solutions that the process of adjustment is accomplished by 

 recrystallization at least to such an extent that the granules do not, on the 

 average, decrease in size. In this fact of increased surface of action for 

 the solutions by granulation we have the explanation of the fact that 

 granulation is not known to produce particles the average of which is near 

 the limit of observation with a moderate power of the microscope. 



An excellent example of the influence of the character of the material 



a Adams, F. D., Report on the geology of a portion of the Laurentian area lying to the north of the 

 Island of Montreal: Ann. Kept. Geol. Surv. Canada, new ser., vol. S, 1895, pt. j, pp. 85-134. 



