The Structure and Distribution of Coral Reefs | Page 7

the
structure of the islands given by Nelson and other authors, and
maintained that the facts observed in them are opposed to the views of
Darwin. Although, so far as I am aware, Darwin had no opportunity of
studying and considering these particular objections, it may be
mentioned that two American geologists have since carefully
re-examined the district--Professor W.N. Rice in 1884 and Professor A.
Heilprin in 1889--and they have independently arrived at the
conclusion that Dr. Rein's objections cannot be maintained.
The most serious opposition to Darwin's coral-reef theory, however,
was that which developed itself after the return of H.M.S. "Challenger"
from her famous voyage. Mr. John Murray, one of the staff of
naturalists on board that vessel, propounded a new theory of coral-reefs,
and maintained that the view that they were formed by subsidence was
one that was no longer tenable; these objections have been supported
by Professor Alexander Agassiz in the United States, and by Dr. A.
Geikie, and Dr. H.B. Guppy in this country.
Although Mr. Darwin did not live to bring out a third edition of his
"Coral-Reefs," I know from several conversations with him that he had
given the most patient and thoughtful consideration to Mr. Murray's
paper on the subject. He admitted to me that had he known, when he
wrote his work, of the abundant deposition of the remains of calcareous
organisms on the sea floor, he might have regarded this cause as

sufficient in a few cases to raise the summits of submerged volcanoes
or other mountains to a level at which reef-forming corals can
commence to flourish. But he did not think that the admission that
under certain favourable conditions, atolls might be thus formed
without subsidence, necessitated an abandonment of his theory in the
case of the innumerable examples of the kind which stud the Indian and
Pacific Oceans.
A letter written by Darwin to Professor Alexander Agassiz in May
1881 shows exactly the attitude which careful consideration of the
subject led him to maintain towards the theory propounded by Mr.
Murray:--"You will have seen," he writes, "Mr. Murray's views on the
formation of atolls and barrier-reefs. Before publishing my book, I
thought long over the same view, but only as far as ordinary marine
organisms are concerned, for at that time little was known of the
multitude of minute oceanic organisms. I rejected this view, as from the
few dredgings made in the "Beagle", in the south temperate regions, I
concluded that shells, the smaller corals, etc., decayed and were
dissolved when not protected by the deposition of sediment, and
sediment could not accumulate in the open ocean. Certainly, shells, etc.,
were in several cases completely rotten, and crumbled into mud
between my fingers; but you will know whether this is in any degree
common. I have expressly said that a bank at the proper depth would
give rise to an atoll, which could not be distinguished from one formed
during subsidence. I can, however, hardly believe in the existence of as
many banks (there having been no subsidence) as there are atolls in the
great oceans, within a reasonable depth, on which minute oceanic
organisms could have accumulated to the depth of many hundred feet."
Darwin's concluding words in the same letter written within a year of
his death, are a striking proof of the candour and openness of mind
which he preserved so well to the end, in this as in other controversies.
"If I am wrong, the sooner I am knocked on the head and annihilated so
much the better. It still seems to me a marvellous thing that there
should not have been much, and long-continued, subsidence in the beds
of the great oceans. I wish some doubly rich millionaire would take it
into his head to have borings made in some of the Pacific and Indian
atolls, and bring home cores for slicing from a depth of 500 or 600
feet."

It is noteworthy that the objections to Darwin's theory have for the most
part proceeded from zoologists, while those who have fully appreciated
the geological aspect of the question, have been the staunchest
supporters of the theory of subsidence. The desirability of such boring
operations in atolls has been insisted upon by several geologists, and it
may be hoped that before many years have passed away, Darwin's
hopes may be realised, either with or without the intervention of the
"doubly rich millionaire."
Three years after the death of Darwin, the veteran Professor Dana
re-entered the lists and contributed a powerful defence of the theory of
subsidence in the form of a reply to an essay written by the ablest
exponent of the anti-Darwinian views on this subject, Dr. A. Geikie.
While pointing out that the Darwinian position had been to a great
extent misunderstood