DIASTROPHISM AND THE FORMATIVE PROCESSES 687 
of various sorts mixed by the chance of infall, it would offer almost 
ideal conditions for recombination, readjustment, and reorganiza- 
tion, which, in this case, would run hand in hand with diastrophism 
and contribute to it. 
4. Relative exhaustion of potential energy by segregation.—li 
the earth was fluid until fully assembled, there should have been 
facilities for the arrangement of the earth substances in concentric 
layers according to specific gravity. This would have been a 
special means of reducing to the lowest terms the potential energy 
that might otherwise have remained available for deformative 
work after solidification made a diastrophic record possible. If, 
on the other hand, the matter remained a heterogeneous mixture 
so far as intrinsic heaviness was concerned, a corresponding amount 
of potential energy remained available for the diastrophic record. 
In so far as segregation by gravity took place during the com- 
pression of the mixed solid mass, it co-operated with other deforma- 
tive processes and left its effects in the record. 
5. Relative exclusion or retention of gaseous consittuenis.—lf 
the earth remained fluid and convective until fully assembled, 
the gaseous constituents should have had favorable opportunities 
for escape and should have been impelled to escape by the very 
high heat, so that only such quantities as were required to balance 
the partial pressures of the same constituents in the atmosphere 
should have remained to take part in vulcanism later. On the 
other hand, if the earth was built up by solid particles added slowly 
to the surface and subjected to weathering and to mixture with 
air and water, as it was gradually buried, the complex should have | 
afforded almost ideal conditions for the evolution of volcanic gases 
when it was later subjected to heat and pressure. The phenomena 
of the moon are especially instructive in this respect, for the gravity 
of the moon is insufficient to hold free volcanic gases even in its 
present cold state; much less then in a hypothetical molten state. 
No equilibrium factor should have been retained in this case. 
But the evidences of vigorous explosive action on the moon are 
very pronounced. 
* Rollin T. Chamberlin, ‘‘The Gases in Rocks,” Jour. Geol., Vol. XVII (1909), 
Ppp- 565-68. 
