66 vaughan: virgin and leeward islands 



position of reefs on antecedent platforms which have undergone 

 geologically Recent submergence. E. C. Andrews so interprets 

 the conditions of formation of the barrier reefs off the Fiji Is- 

 lands. 7 It appears to me that the conditions governing the 

 development of the living reefs in the West Indies, Central 

 America, Brazil, Florida and Australia are clear. The reefs 

 have grown upon antecedent basements during Recent sub- 

 mergence. The history of these basements is complex, but dur- 

 ing Pleistocene time they stood higher with reference to sea-level 

 than now, their outer margins were remodeled by marine cutting 

 and marine planatidn, and they were then resubmerged. These 

 changes in height of sea-level accord with the demand of the 

 glacier control theory. It would be remarkable if the conditions 

 in the tropical western Pacific Ocean were exceptional, and 

 the present available facts indicate that they conform to the 

 principles governing reef development in the other areas. Here 

 it should be said regarding the charts for the Pacific, that as 

 they have been made primarily for navigation purposes the 

 depths of lagoons and lagoon channels are often given in a way 

 fairly satisfactory, but on only a few charts can the submarine 

 profiles outside the reefs be determined. The coral reef prob- 

 lem cannot be regarded as satisfactorily solved until the rela- 

 tions in the Pacific islands have been ascertained. In my opinion 

 but little further advance in understanding the problem can be 

 expected from purely biologic studies or from physiographic 

 investigations of the dry land surface alone. As apparently 

 the greatest present need is for more accurate information on 

 the detailed submarine relief in depths between 15 and 50 fathoms, 

 especially on the seaward margins of the platforms, both outside 

 the reefs and off the breaks in the reef lines, the efforts of those 

 interested in such investigations should be concentrated on 

 getting additional hydrographic surveys in coral reef areas. 



1 Am. Jour. Sci. 41: 135-141. 1916. 



