JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VI FEBRUARY 4, 1916 No. 3 



GEOLOGY. — Some littoral and sublittoral physiographic features 

 of the Virgin and northern Leeward Islands and their bearing 

 on the coral reef problem. Thomas Wayland Vaughan, 1 

 Geological Survey. 



The Virgin Islands rise above a bank extending eastward from 

 Porto Rico from which they are separated by water up to 17 

 fathoms deep. The St. Martin group, comprising Anguilla, 

 St. Martin, St. Bartholomew, and a number of islets, lie a little 

 south of east from the Virgins across the Anegada Passage, 

 which exceeds 1000 fathoms in depth. St. Croix is due south 

 of the Virgins across a chasm, a great fault valley, which at a 

 distance of 22^ miles south of St. Thomas attains a depth of 

 2580 fathoms (15,480 feet). Saba is south of St. Martin. The 

 west end of the St. Christopher Chain, to which St. Eustatius, 

 St. Christopher, and Nevis belong, is south of St. Bartholomew; 

 while Antigua and Barbuda are east of the St. Christopher Chain. 



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 St. Christopher Chain, 

 into the sides of which the sea has cut relatively narrow plat- 

 forms (see fig. I). 2 There are suggestions of submerged flats 

 off the northwest end of St. Eustatius and southeast of Nevis. 



1 Published by permission of the Director of the U. S. Geological Survey and 

 of the President of the Carnegie Institution of Washington. 



2 The profiles illustrating this paper were draw by Miss Irene Pistorio, who 

 also drew the contours on the hydrographic charts here discussed. 



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