UNCONFORMABLE ELEVATED REEFS 



507 



unconformably on a sloping surface of subaerial erosion, perhaps clift at 

 the base; only the exterior tains deposits can lie conformably on a non- 

 eroded volcanic slope, and even these may, in certain cases noted below, 

 lie unconformably on a slope of subaerial erosion. 



UNCONFORMABLE ELEVATED BEEFS IN FIJI 



Furthermore, it would not seem to require a very penetrating use of 

 scientific observation to determine which one of these contrasted conse- 

 quences is confirmed by the facts. Elevated reefs in particular should 

 offer excellent opportunity for applying so crucial a test, and, as will ap- 

 pear below, their unconformable contacts have truly enough been noted in 

 a fair number of cases; but unhappily this important matter has ordi- 



FiGURE 5. — Contrasted Consequences of Murray's and Darwin's Theories 



narily been overlooked, and even when noted the consequences following 

 from it have not usually been correctly inferred. One of the best exam- 

 ples of the kind that has come to my own attention, and of which I have 

 already given a brief account (1915, 250), is found on Vanua Mbalavu, 

 one of the Exploring Isles that are inclosed in a great barrier reef, 23 

 miles in longest diameter, in the eastern part of the Fiji group. Here 

 the largest volcanic island, 13 miles in length, partly shown in figure 6, 

 has a maturely carved form, and rises to an altitude of 930 feet; it is in 

 part unconformably covered up to heights of 500 or 600 feet, as shown 

 diagrammatically in sector E, by a deeply dissected and well embayed 

 mass of limestone, which is therefore probably, as Agassiz said, the "frag- 

 mentary remains of the land which must have once occupied the area of 

 the lagoon," now inclosed by the great barrier reef. 



