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BULLETIN 103j UNITED STATES NATIONAL MUSEUM. 



is not composed of marine plants (according to Mr. C, A. Davis), 

 adds confirmation to the inference from the indented shore hne and 

 the absence of elevated terraces and wave-cut cliffs that the last 

 important movement of the strand line was one of submergence. 

 Present sea-level relations have persisted long enough for the develop- 

 ment of sea cHfFs, in places 100 feet or more high, for the alluvial 

 filhngs at the heads of the bays, and for the extension inland of 

 alluvial deposits along the streamways. There is some evidence of a 

 slight upward movement of the land, a few feet, less than 10, since 

 the submergence. 



Fig. 10.— Chart of paet of east coast of antigua. From U. S. hydeogbaphic chart no. 1004. 



Barbuda, which is composed of hmestone and has a maximum 

 height of about 200 feet, has no marked indentations of its shore 

 line; but Dr. H. A. Tempany informs me that fresh-water springs 

 emerge below sea level in the lagoon about one-half mile south of 

 Codrington village, a fact of significance in probably indicating 

 submergence. 



The similarity of the land mollusca of Antigua and Barbuda lend 

 support to the inference from physiographic data that these islands 

 were part of one land mass in Pleistocene time and have been severed 

 by submergence, and as the water between the islands is 18 fathoms 

 deep, the sea level must have risen at least that amount. A sub- 

 merged steep slope off the southeast side of Antigua at depths be- 

 tween 100 and 150 feet accords with submergence to a depth of at least 



