ABSTKACTS AND DISCUSSIONS OF PAPERS 41 



American Society of Vertebrate Paleontology on December 26, 1907, but liave 

 been withheld from publication. The present presentation will place the 

 emphasis on the more general aspects and consequences of the problems of the 

 Devonian climates in relation to the rise of air-breathing vertebrates. It is 

 intended to publish the papers in the near future. 



Presented in abstract extemporaneously. 



SOME LITTORAL AND SUBLITTORAL PHYSIOGRAPHIC FEATURES OF THE 

 VIRGIN AND NORTHERN LEEWARD ISLANDS AND THEIR BEARING ON 

 THE CORAL-REEF PROBLEM 



BY THOMAS WAYLAHD VAUGHAN 1 



(Abstract) 



The ocean bottom off the shores of the Antilles shows three distinct types of 

 profiles, and a fourth type is furnished by Saba and other banks. The first 

 is that found off the volcanic islands, such as Saba and the members of the 

 Saint Christopher Chain, into the sides of which the sea has cut relatively 

 narrow platforms ; but there are suggestions of submerged flats off the north- 

 west end of Saint Eustatius and southeast of Nevis. 



The second type of submarine profile is well represented off the north shore 

 of Saint Croix and the south shore of Cuba. The precipitous character of 

 these profiles indicates faulting, and the geologic structure supports this in- 

 terpretation. There is a down-thrown block between the Virgins and Saint 

 Croix and another between Cuba and Jamaica. 



The third type of profile, represented by shores off which are extensive 

 shallow flats, occurs where planation agencies have long been active. Here 

 the rocks often, if not usually, dip under the sea at relatively gentle angles. 



The fourth type of profile is represented by the extensive submerged banks 

 or platforms which have no bordering lands and whose upper surfaces range 

 in depth from 9 to 30 fathoms. Good examples are Saba Bank, southwest of 

 Saba Island : Pedro Bank, southwest of Jamaica, and Rosalind Bank, off 

 Mosquito Bank, which is the continental shelf northeast of Nicaragua and 

 Honduras. That the depth of water on these banks is essentially the same 

 as in many atolls of the Pacific, especially the Paumotus, has been repeatedly 

 pointed out, but apparently the fact has not yet been sufficiently emphasized. 



The third type of profile (that showing submarine terraces around islands) 

 will now be discussed in some detail. From shoreline characters and other 

 evidence the conclusion was reached that the Virgin Islands, the members of 

 the Saint Martin group, and Antigua and Barbuda have recently undergone 

 submergence to an amount of about 20 fathoms. 2 Assuming this conclusion to 

 be correct, should the sealevel have remained stationary for a period of ap- 

 preciable length antecedent to this submergence, there should be a submerged 

 scarp or facet indicating its former stand ; should there have been a succession 

 of temporary stands, there should be a series of submarine terrace flats 

 separated by scarps. The available sources of information were the charts of 



1 This article, illustrated by more than fifty profiles and a map, Is published In the 

 Jour. Wash. Acad. Sci., vol. 6, pp. 53-56, Feb. 4, 1916. 



2 Bull. Am. Oeog. Soc, vol. 46, 1914, pp. 426-429. 



