MASS DYNAMIC ACTION. Bil 
depth the spacing between the joints and faults decreases until the frac- 
turing is that of fissility or of granulation. 
It is therefore clear that the amount of energy required for fractures 
a considerable distance apart, such as prevail where joints or faults, or 
both, are the dominant deformations, is less than that required for the 
equivalent deeper-seated deformation, where the fractures are close to- 
gether—as, for instance, in the case of fissility. Furthermore, it is clear 
that the amount of energy required for the slicing of fissility is much less 
than that required for granulation of the individual particles, for in the 
latter case a mass equivalent to a fissile leaf must be broken into a multi- 
tude of particles. Probably the ratio between the energy required for 
breaking a rock into joint or fault blocks near the surface and that re- 
quired to produce fissile leaves deeper down is not greater than the ratio 
between the energy required to produce fissility and that required to pro- 
duce granulation throughout at a still greater depth. No general ratio 
between the amount of energy spent in deformation by joints and faults 
and deformation by granulation can be given; but it is certain that the 
amount of energy used in the extreme cases of the latter may be indefi- 
nitely greater than that required for the former. 
Since it is certain that in passing from the surface to considerable depth 
there is a passage from deformation by jointing or faulting, or both, to 
deformation by granulation, it is certain that to a depth of a number of 
thousand feet there is a steady and very rapid increase in the amount of 
energy required for a given mass deformation. 
At sufficient depth, as has been seen, granulation is more and more 
replaced by recrystallization, and finally this process is dominant. It 
would be very interesting to know exactly the relative amounts of energy 
required for the two processes of granulation and recrystallization. 
As already noted, the energy required for granulation is wholly me- 
chanical and includes three factors: (1) that required for the subdivision 
of the rocks, (2) that required for transfer of material, and (8) that re- 
quired to overcome friction. 
The energy factors in recrystallization are four in number: 
(1) Energy is continuously used in straining minerals during defor- 
mation; but it is impossible to determine the amount of straining which 
takes place, for evidence of the strain is continuously obliterated by 
solution and deposition. Ifthe mechanical stresses did not continuously 
produce a state of strain, and thus disturb the equilibrium, it is probable 
that the rate of the process of solution and deposition would be very 
slow. It is this constant work in producing strain that keeps the pro- 
cess of recrystallization going. 
(2) Hnergy is required for the transfers of materials by solution. 
