MEANING OF ROCK FLOWAGE. 759 



The illustrations of the perfect schists produced mainly by recrystalli- 

 zation, and of the imperfect schists produced by recrystallization and 

 mechanical strains combined, are so well known that they need not be 

 mentioned. The best illustration known to me of fiowage mainly by 

 granulation is afforded by the anorthosites of the Original Laurentian, 

 described by Adams." 



So far as the mass deformation is concerned, the rock fiowage may be 

 mainly by recrystallization, mainly by granulation and other mechanical 

 processes, or by any combination of them. In all alike there is minute 

 interior adjustment of the particles so as to change the mass form of the 

 rock. It makes no difference, so far as the resultant form is concerned, 

 whether the change is accomplished mainty by the differential movements 

 of the molecules, as in the recrystallized schists, or by the differential 

 movements of granules, as in the cataclastic rocks, or by the two combined. 



CONCLUSION. 



Rock flow is mainly accomplished through continuous solution and 

 deposition — that is, by recrystallization of the rocks through the agency of 

 the contained water. The recrystallization is largely induced by mechanical 

 strains. Rock flow is partly accomplished by direct mechanical strains. 

 At the beginning' of the process of flow, during the process, and at the end 

 of the process, the rocks, with the exception of an inappreciable amount, 

 are crystallized solids. At any moment only an infinitesimal quantity is 

 fluid — that contained in the minute quantit}^ of water present. Yet the 

 solids respond to deformation like plastic bodies, not only not losing* crys- 

 talline character, but usually acquiring mineral particles of fair magnitude, 

 because the water is ever changing' the position of the crystallized material, 

 dissolving a substance here and depositing- it there. By this process, 

 combined with the mechanical strains, there is continuous adjustment or 

 adaptation of the mineral particles to their environment, as demanded by 

 the deformation of the rock. 



This is rock flow. In this conclusion nothing is said as to the condition 

 of material below that part of the earth which is called the lithosphere, nor 

 as to the meaning of flow in this part of the globe — i. e., the centrosphere. 



"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. 8, 1895, pt. j, pp. 103-131. 



