MAYOR— THE REEFS OF TUTUILA, SAMOA. 



227 



I find upon contouring this chart (Fig. 2) that it indicates that 

 Tutuila was once surrounded by a wide barrier reef and that also 

 a well-developed fringing reef extended out from the shore and 

 fused in many places with the barrier reef, obliterating the lagoon 

 between them. This fusion of the two reefs was well seen along 

 the north coast between Vatia and Maloata, but it occurred also on 

 the south coast ofif Cocoanut Point. The lagoon between the bar- 

 rier and the fringing reef of the southern coast of Tutuila was in 

 many places at least 20 fathoms deep ; but along the north coast 

 between Vatia and West Cape it was shallower and was thus largely 



De^iVit in FatSomt 



Liss thi>n 11 r*»>iiim». 

 100 Fathom L^nt 



Fig. 2. The dotted areas show the ancient barrier and fringing reefs 

 which once surrounded Tutuila but are not submerged about igo feet below 

 sea level. 



obliterated by the fusion of the fringing reef with the barrier, for 

 the lagoon between these reefs was in most places not more than 2 

 to 4 fathoms in depth. 



As was suggested by Daly this greater depth of the lagoon along 

 the southeastern shore indicates that there was an actual subsidence 

 of the island itself, the southeastern coast sinking more than the 

 northern shore: At any rate these ancient barrier and fringing 

 reefs are now submerged to a depth of about 30 fathoms. As reef- 

 building corals can grow only sparingly at depths greater than 

 about 18 to 20 fathoms, these ancient reefs are drowned and in 

 most places are probably not at present growing upward. In many 

 parts of the Taema and Nafanua Banks, however, the depth is now 

 less than 18 fathoms and modern corals are growing in patches in 



