GLACIAL-CONTROL THEORY OF CORAL REEFS. 217 



A number of large banks in the coral seas have either no projecting 

 reef rims at all or else have merely local raised patches of coral on 

 their edges. Examples are here listed (Table V). 



These cases are more difficult of explanation. The Seychelles bank, 

 for example, does not now lie in the path of frequent hurricanes, and, 

 so far as the -^Titer can find records, the Seychelles area has moderate 

 weather the year around.*^ Similarly, part of the Laccadive plat- 

 forms are provided with atoll reefs reaching the surface, while others 

 are still flat banks lacking peripheral reef crowns. It is possible that 

 the rimless banks not now lying in hurricane paths have been affected 

 by hurricanes during some earlier fraction of post-Glacial time, as the 

 climatic zones of the Pleistocene slowly shifted to their present posi- 

 tion. 



The unrimmed banks above listed, as well as others within the 

 tropics, have average depths of just the same order as those found on 

 many banks outside of the coral seas, e. g., the Tanner, Cortes, and 

 Osborn banks off California. As already noted, such accordance 

 finds no systematic place among the consequences of the subsidence 

 theory, but is expressly demanded by the Glacial-control theory, if 

 these intertropical banks have been little modified by post-Glacial 

 growth of coral, and if sea-level has undergone little change since the 



48 A. Voeltzkow (Geog. Anzeiger, Jahrg., Heft 1, p. 5 (1907)) states that, 

 so far as he saw during his extensive travels, the whole western part of the 

 Indian ocean is remarkably devoid of strong reefs composed chiefly of living 

 corals, though limestones enclosing isolated corals do form banks. He speaks 

 of the local patches of growing corals ("Korallengarten") as secondary forma- 

 tions, having no close relation (" ohne jede nahere Beziehung") to the platforms 

 on which they rest. 



