92 Applications of the Igneous Theory of the Earth. 
present us with islands or submarine mountains, according to 
their elevation relatively to the oceanic surface. These inclined 
portions of the earth’s crust, resting on the central fluid of greater 
specific gravity than themselves, and pressed firmly together at 
their lower angles by their own weight, constitute the bed of 
ocean and the principal marine divisions. 
If these are legitimate deductions from the geological theory, 
it is manifest that by virtue of the gradual contraction of the 
central fluid, the inequalities of the earth’s surface are from age 
to age increasing ; that in the gross, the elevation of continents 
and islands above the surface of the ocean is gradually becoming 
‘greater ; that the land is encroaching upon the water, or in other 
words, that the level of the sea is from time to time assuming a 
lower position with reference to fixed points on the shore. I say 
in the gross, for partial causes may operate to vary the result in 
particular cases; and even extensive lines of coast may be so 
situated as to exhibit the contrary phenomenon. On the princi- 
ples of the theory, however, the general rule must be as stated. 
Indeed, in view of the local evidences of this recession of the 
waters, nothing is now more common with the geologist than to 
assign, as a cause of the phenomenon, the “ upheaving” of the 
contiguous portion of the earth’s surface. These are but par- 
ticular cases under the general law. By way of illustration we 
may refer to those islands whose soil rests on a continuous sub- 
stratum of coral. Now it is well known, that the coral formation 
is of submarine origin, and its appearance above the surface can 
be accounted for only by the “upheaving” of the apex of the 
submarine mountain on which its growth took place. 
The fragmentary character of the earth’s crust would seem to 
be strongly attested by the phenomena of earthquakes. These 
phenomena, in all their extent and variety, are wholly irrecon- 
cilable with the supposition that the structure of the earth is solid 
throughout. And adopting on the other hand the hypothesis 
of an unbroken and sulf-sustained shell, enclosing a central fluid, 
it would be difficult to avoid the conclusion that all earthquakes 
must be universal in their extent. Physical action commencing 
in any part of the shell, could hardly fail to send its vibrations 
eh the whole. It is matter of experience, however, that 
phenomena are not thus universal. Some are of compara- 
-Gvdlipalaeil extent, while others affect considerable portions of 
y 
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