CORAL REEFS AND SUBMARINE BANKS 307 
an original [still-standing] land mass, or more probably series of 
masses,’ and that the present shoals and reefs were aiterward 
built up from the plateau to the sea surface.' He thus assumes, 
as Wharton did in his abrasion theory of atolls, that destructive 
processes first wore down a non-subsiding land mass or series of 
masses to a certain depth—in the case of the Maldives to the 
considerable depth of 150 fathoms—and that organic agencies, 
which must have been in abeyance while the down-wearing was 
in progress, then proceeded to overcome the destructive processes 
and to build up the present shoals and reefs. A hypothesis which 
accounts for the Maldives by upgrowth on a series of worn down, 
still-standing land masses might also explain a number of large 
submarine banks, imperfectly reef-rimmed, as still-standing masses 
that have been similarly worn down and are not yet completely 
built up again; but neither the postulates nor the processes of 
this hypothesis commend it. 
Between the two extremes thus instanced Darwin’s theory of 
reef upgrowth during intermittent subsidence seems to me a happy 
mean. Darwin applied his theory to the Maldives in a manner that 
is still consistent with the best interpretations of oceanographic 
problems; he regarded those numerous atolls in linear arrangement 
as-resulting from the disseverment of a great barrier reef upgrowing 
from a slowly subsiding foundation 
of nearly the same dimensions with that of New Caledonia ... . for if, in 
imagination, we complete the subsidence of that great island, we might antici- 
pate from the present broken condition of the northern portion of the reef . . . . 
that the barrier reef, after repeated subsidences, would become during its 
upward growth separated into distinct portions; and these portions would 
tend to assume an atoll-like structure, from the coral growing with vigour 
round their entire circumferences, when freely exposed to an open sea [r1o]. 
Similarly Darwin’s explanation of submarine banks by subsidence 
is more in accordance with all pertinent facts than is any explana- 
tion which involves their long-enduring stability. Whether the 
failure of reefs to grow up from such banks to the surface again is 
due to rapid subsidence, as Darwin thought, or to the injurious 
tJ. S. Gardiner, ‘‘The Origin of Coral Reefs,” Amer. Jour. Sci., XVI (1903), 
203-13; See pp. 205, 200. 
