CORAL REEFS AND SUBMARINE BANKS Ae 
of atoll-lagoon floors occurring at similar depths are thought to 
demand the narrow limitation of general stability for their 
production. 
It is true that the fullest exposition of the glacial-control theory 
contains certain statements which admit the exceptional occurrénce 
of subsidence, such as: ‘“‘ The glacial-control theory fully recognizes 
that there has been Recent crustal warping in certain oceanic areas 
affected by coral reefs” (160°); and ‘‘perfect crustal stability in 
the intertropical zone during the Recent and Pleistocene periods 
is obviously not implied in the glacial-control theory” (222); but 
it also contains many statements of an opposite tenor which relegate 
subsidence to an insignificant position in the coral-reef problem. 
For example: 
Most of the reef platforms, like many banks situated outside the coral seas, 
have such forms, dimensions, and relations to the sea-level that they appear to 
have originated during a long period of nearly perfect stability for the general 
ocean floor. That is a conclusion forced upon the writer by close study of the 
marine charts. Its validity is a matter quite independent of the glacial- 
Controls theonyeaey sss: Submarine topography [of lagoons and banks] seems 
impossible of explanation without assuming crustal quiet beneath most of the 
deep sea during at least the later Tertiary and Quaternary periods [162]. 
Large preglacial volcanic islands are assumed to have stood still 
long enough to have been “‘peneplained and deeply decayed before 
the glacial period’? (182). The preglacial degradation of such 
islands and their abrasion at normal sea-level, partly in preglacial 
time during temporary failures of reef protection, partly by the 
chilled and lower waters of the glacial ocean, demand 
much of the later Tertiary as well as the Pleistocene period, and thus during 
several million years the relation of sea bottom and sea surface was not sig- 
nificantly changed. However, such crustal stability is necessarily postulated 
only for the parts of the coral seas where broad platforms, about 75 m. below 
sea-level, are now found. For those areas the assumption of prolonged crustal 
stability, except for minute oscillations, seems absolutely unescapable. All 
theories of coral reefs must recognize it... . . The presence of a wide shelf 
or bench [lagoon floor ?], a few tens of meters below sea-level, really represents 
a criterion for crustal stability during the later geological periods, generally 
including at least the time since the mid-Pliocene. The existence of the broad 
1 References to Daly’s paper, ‘‘The Glacial-Control Theory of Coral Reefs,” 
Proc. Amer. Acad., LI (1915), 157-251, will be made by page number only. 
