484 
Van Rise—Earth Movements. 
a part of the continental land sinks below the level of the water. 
After an area has subsided below the water, it has been supposed 
that for some unknown reason titanic forces below pushed up the 
continents against gravity, but in favor of such a supposition no 
adequate reason was given. As has been seen it cannot be sup¬ 
posed that the great continental masses have anywhere been by 
any forces pushed farther from the center of the earth, unless 
at the same time another mass approached nearer the center of 
the earth. However, the continents would emerge from the 
sea if the sea bed sank upon the average faster than the conti¬ 
nents, as certainly as they would if the continental masses rose 
absolutely, and this, it is believed, is the explanation of the 
emergences of the continents from the sea. 1 
When a great subsidence of a sea or land area anywhere oc¬ 
curs, the only possible earth movement which, in the first event, 
would avoid elevation with reference to the sea of all of the con¬ 
tinents an amount equal to the subsidence, and in the second 
event other parts of the continents, a much smaller amount, is 
the equal simultaneous subsidence of all the land masses at the 
same rate as one another, and at the same rate as the average 
subsidence of the sea beds. That such a remarkable adjustment 
should at any time occur is highly improbable, and therefore, 
it is to be expected that relative subsidence or elevation is at 
all times somewhere taking place. 
If the above theory of great continental submergences and 
emergences by differential subsidence be true, it would follow, as 
just explained, that the emergence of one land area by the sink¬ 
ing of the sea bottom faster than the land area would be ac- 
1 The fundamental idea involved in this explanation was stated by Con¬ 
stant Prevost many years ago. (Loc. cit., p. 186.) I quote Dana’s transla¬ 
tion (Am. Journ. Sci. & Arts, H, Vol. 3, 1847, p. 179): 
“ Are we not then forced to admit that while the bottom of the sea has 
been raised above the level of the sea and made dry land, by a series of dis¬ 
placements, still larger terrestrial areas have disappeared from submer¬ 
gence; and in such a way that the depressions formed were greater than 
the elevations, a condition without which, I repeat it, the low parts of our 
existing continents could not have been emerged, a condition requiring for 
its fulfillment, no aid from the suppossed agent of ‘ soulevement,’ since this 
would produce a contrary effect.” 
