in the Pleistocene and Post-Pleistocene. 



7 



miles from shore. Then comes a convexity and a descent, in 

 places to great depth, in other places, as illustrated by the 

 shelf seas of Argentina, to broad flats about twenty fathoms 

 deeper. Daly has been independently following the very 

 same line of investigation, and he states in a personal 

 communication that he has reached the conclusion that effective 

 wave action stops much above the one hundred fathom line, 

 notwithstanding that this has become conventionally accepted 

 as the limit. With this conclusion the writer is in accord. 

 Vaughan also has called attention to precisely the feature of 



Fig. 2. 



^^^ 







^~~r~— =-*— •. 



. . 





. 



"\ 



20 

 30 

 40 



Wes^ coast Madagascar LotS I8°s: 



t to I9 a 03' \ 



\z 





\z 





r 





O FATHOMS 



Sourheasr coasr Madagascar 

 BeriueenC.Ronovalona and Galleon Bay LaK S. 25°05' 



Fig. 2. Subaqueous projected profiles, coasts of Madagascar. Most of the 

 coast shows graded, subaqueous profiles in adjustment with the present 

 level of the sea, the wave action being relatively weak on the western side, 

 strongest on the southeast. The figure shows how the different exposures of 

 a coast mast be considered together in order to eliminate the varying effect 

 of the waves according to their intensity. This permits a conclusion 

 regarding the relation of the profile to present and past water levels. 

 Vertical scale 100 times horizontal. 



the ocean profiles here described, noting the steep descent 

 from about the 30-fathom to the 50-fathom curve, with gentler 

 slopes above and below, as seen especially on the North 

 American and Australian platforms.* E. C. Andrews, a 



* Sketch of the Geologic History of the Florida Coral Eeef Tract, and 

 Comparison with Other Coral Eeef Areas, Jour. Wash. Acad. Sci., p. 33, 

 1914. 



The Platforms of Barrier Coral Reefs. Abstract, Bull. Am. Geog. Soc, 

 vol. xlvi, p. 427, 1914. 



