MASS DYNAMIC ACTION. BIZ 
the mass during deformation under these different conditions, for if this 
could be done it would be possible, at least in this case, to make some 
quantitative estimate of the relative energy demanded by deformation 
through granulation and through recrystallization. Doubtless this would 
be a difficult task. It would be necessary to separate the total work 
done in the machine into the parts which were required for the deforma- 
tion of the rock mass and that required for the deformation of the sur- 
rounding iron, and in one case also to estimate the energy furnished by 
the water. If it were possible to make the determination, I anticipate 
from the analysis of the previous pages that the energy required for de- 
formation through recrystallization would be much less than that re- 
quired for deformation through granulation. 
Of course, the question arises, in the cases of mountain-making, if less 
energy is required for recrystallization than for granulation, why the 
latter process occurs. The answer is plain. Recrystallization cannot 
occur except where there are the proper conditions of temperature and 
moisture. If the nucleus of the earth is shrinking, the outer crust must 
be reduced in size to accommodate itself to this nucleus. This implies 
crustal deformation which extends to the surface, and therefore to places 
where the conditions are not such that recrystallization can take place. 
From the foregoing considerations, I believe that the amount of work 
done, in order to produce the same mass deformation of the rocks, in- 
creases to a certain depth and then decreases for a certain depth. How 
far down this decrease continues I am unable to conjecture, but believe 
it is probable that the decrease continues at least as deep as the zone in 
which the schists formed by recrystallization develop, and may continue 
much farther. 
The deformation of this deep-seated zone may or may not require the 
elevation of the superincumbent mass. Where the superincumbent mass 
is not.elevated it is therefore concluded that the energy required for 
deformation per unit mass is very much less than that required for gran- 
ulation and may be less than that required to produce the spaced frac- 
tures which occur near the surface. Where the deformation is of the 
kind which requires the elevation of the superincumbent material, en- 
ergy is needed not only to do interior work of deformation, but to elevate 
this material. Where these conditions obtain it may be possible that the 
amount of energy required to produce the deformation may steadily in- 
crease with depth on account of the energy required for lifting the load in 
addition to that required for the interior deformation. 
So far as I know, the best region in America which illustrates all the 
phenomena from deformation by joints and widely spaced thrust faults 
XLVII—Buur. Gror. Soc. Am., Von. 9, 1897 
