26 
ANNALS NEW YORK ACADEMY OF SCIENCES 
of the earth’s crust; but it was clear that elevation could not bring about the 
conditions, as that would destroy the corals themselves; subsidence alone 
can account for the phenomena. And thus Darwin presents his case: 
If then the foundations of the many atolls were not uplifted into the requisite 
position, they must of necessity have subsided into it; and this at once solves every 
difficulty, for we may safely infer from the facts given in the last chapter, that during 
a subsidence the corals would be favorably circumstanced for building up their 
solid fra m ework and reaching the surface, as island after island slowly disappeared. 
Thus areas of immense extent in the central and most profound parts of the oceans 
might become interspersed with coral islets, none of which would rise to greater 
height than that attained by detritus heaped up by the sea, and nevertheless they 
might all have been formed by corals which absolutely require for their growth a solid 
foundation within a few fathoms of the surface.The rocky bases slowly 
and successively sank beneath the level of the sea, while corals continued to grow 
upward. 
The origin of the ring as well as that of the barrier reef seemed to be 
easily explained by this hypothesis. The corals on the outer side of the 
reef grew with greater rapidity than did those within, as the supply of food 
is constant; those on the inner side became starved and eventually the 
interior growth ceased, and the lagoon was shallowed by wind-drifted 
material from the shores. 
Darwin’s hypothesis and the facts on which it was based have become 
so familiar that students sometimes express surprise that so much praise 
has been awarded to the author. The conditions as presented in his dis¬ 
cussion are so clear that certainly no man could reach any other conclusion. 
That is true, but it is true only because Darwin marshalled his facts in a 
manner so masterly; in any event, it is always easy to do a thing, when 
another has done it well and told us how. But it must be remembered that 
a hypothesis of this sort, though normal enough in our day, was very ab¬ 
normal in that day; indeed, it was contrary to Darwin’s own underlying 
conceptions, for, though a uniformitarian, he had seen many phenomena 
which, for a time,' made him only a halting disciple. Yet his hypothesis 
was a monumental contribution in support of the uniformitarian doctrine, 
which, under the leadership of Lyell, was gaining sturdy adherents. That 
the hypothesis met with uncompromising opposition need not be said. The 
material of coral origin extended to vast depths alongside of the islands, in 
some cases apparently to 4,000 feet. The upward growth of the reef was 
known to be extremely slow. If the subsidence and the upward growth kept 
pace, as was essential to the hypothesis, evidently the required period, 
belonging to the latest portion of the earth’s existence, was immensely long. 
It is difficult now to understand how great moral courage was needed by 
the man who published such a doctrine; sixty years ago, the educated man 
