70 MAYOR— ROSE ATOLL, AMERICAN SAMOA. 



of the same pink-colored species of lithothamnium (Porolithon) now 

 found growing over the shallows of the reef fiat. 



The atoll rim was once at least 8 feet higher than at present, and 

 has been cut down to present sea level by the lowered ocean of 

 modern times. 



In common with Rose Atoll, all the volcanic islands of American 

 Samoa indicate that sea level was once at least 8 feet higher than 

 at present. 



The rock of the atoll rim contains from about 14 to 19 per cent. 

 of magnesium carbonate, due to its being composed largely of litho- 

 thamnium, but not due to any appreciable dolomitization of the 

 limestone after its formation. 



As fossil corals and lithothamnium are found in the highest parts 

 of the remnants of the old atoll rim, it appears that the climate of 

 American Samoa was tropical at the time when the rim stood at 

 least 8 feet higher than at present. 



