196 T. C. CHAMBERLIN 
It is worth observing that the highly carbonated state of the 
abysmal and polar waters of the present subglacial period leads to 
a large measure of solution of the calcareous relics that fall from 
the pelagic plankton toward the abysmal depths, and this greatly 
limits current oceanic deposits; but this specially solvent state of 
the abysmal waters probably did not obtain during the mild climates 
typical of times of wide sea-transgression. Hence a wider and 
thicker abysmal deposit may be postulated for those times. 
4. Now at a critical stage of this progress when 30 per cent or 
4o per cent of the surface of the continental platforms had become 
covered by the transgressing shelf-seas, let it be assumed that the 
loading and unloading had developed sufficient differential stresses 
in the earth-body to start easement movements by the depression 
of the weighted suboceanic segments on the one hand and the 
relative elevation of the denuded continental segments on the other. | 
These reciprocal movements would be followed by a flow of water 
from the rising continental shelves to the sinking ocean basins. 
This shift of burden from one side of the equation to the other 
would tend to intensify the diastrophic movement. If this new 
emergence returns to a stage comparable with that assumed at the 
outset, all the water-burden upon the sea-shelf, a matter of per- 
haps 300 lbs. or so per square inch, averaged for the whole shelf 
area, will have been transferred in this unrestrained way to the 
abysmal basins, where it will be an added burden of equal value, 
though much more widely and uniformly distributed. In more 
general terms this may amount to a mean unburdening of the 
continental area, considered as a whole, to the extent of about 50 
Ibs. per square inch and a simultaneous mean loading of the whole 
oceanic area of about 25 lbs. per square inch. 
A concurrent enhancement of effect will arise from the ease 
with which the rock mantle accumulated during the base-leveling . 
stage—as well as the soft sediments on the face of the sea-shelfi— 
will be eroded and carried down to the borders of the depressed 
ocean as the continental elevation advances. 
It thus appears that such a general diastrophic movement, in 
the course of its own normal line of action, brings into play an easy 
and prompt shifting of load of a special type that tends to acceler- 
