IMPORTANCE OF WATER IN RECRYSTALLIZATION. 747 



with the freed water, and is squeezed upward to the belt of cementation. 

 (See pp. 177, 667.) 



The foregoing facts seem to show that whether granulation or recrystal- 

 lization occurs in the zone of anamorphism in a g'iven district in rocks of a 

 certain chemical composition does not depend upon whether the rocks are 

 igneous or aqueous, but, other things being equal, upon whether sufficient 

 water is present, by means of which reciystallization can 'occur. As this is 

 more frequently the condition in the sedimentary rocks than in the igneous 

 rocks, the sedimentary rocks are more frequently recrystallized than the 

 igneous rocks, though in many instances recrystallization, rather than gran- 

 ulation, has been the process of modification for the igneous rocks. 



The experimental work of Adams and Nicolson ° upon the deformation 

 of marble seems to me to be fully confirmatory of the above conclusions 

 as to the influence of water in determining whether granulation or recrys- 

 tallization occurs. They deformed marble under conditions of the zone 

 of flowage, both dry and wet, at a temperature of about 300° C The 

 marble deformed while dry, "if not quite as strong, is at least very nearly 

 as strong as the original rock," 6 as shown by tests of its crushing strength, 

 whereas the marble deformed at the same temperature in the presence of 

 steam at a pressure of 460 pounds per square inch was "not weaker, but 

 actually somewhat stronger than the original rock." c While they conclude 

 that "the presence of water was not observed to exert any influence," d they 

 say: "It is just possible, however, that there may have been a deposition 

 of infinitesimal amounts of calcium carbonate along very minute cracks or 

 fissures, thus contributing to maintain the strength of the rock. No signs 

 of such deposition, however, are visible." 6 



It seems to me that the increased strength of the rock deformed in 

 the presence of steam is positive evidence of the influence of water. 

 When it is remembered that the mineral experimented upon was one 

 which is readity deformed by movement along gliding planes, and there- 

 fore one in which for deformation without granulation recrystallization 

 is not necessary, and that the time through which the experiment was 



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

 Trans. Royal Soc. London, series a, vol. 195, 1901, pp. 363-401. 

 b Adams and Nicolson, cit., p. 379. 

 o Adams and Nicolson, cit., p. 385. 

 A Adams and Nicolson, cit., p. 399. 

 'Adams and Nicolson, cit., p. 385. 



