CORAL REEFS AND SUBMARINE BANKS 295 
Furthermore, the zodlogical evidence provided by Crampton’s 
recent elaborate investigations is so strongly confirmatory of the 
subsidence which earlier investigators had inferred from similar but 
briefer studies that the postulate of stability for these islands in 
particular needs revision. Crampton’s conclusion is: ‘‘The occur- 
rence of related forms [of land snails] in Tahiti, Raiatea, and Moorea 
means that in former times these islands were connected by land; 
that the common ancestral stock ranged over the whole land mass, 
and that its local products differentiated into the distinct species 
after the process of subsidence had isolated the mountains now 
forming the separate islands.’ 
No truncated volcanoes are known in the coral seas.—If atolls have 
been formed by the processes of the glacial-control theory, then 
after an atoll is sufficiently uplifted and dissected an abraded 
volcanic platform, around the margin of which the atoll reef was 
built up, should become visible. Most uplifted atolls are either 
not raised enough or not eroded enough to reveal a foundation 
40 fathoms or 240 feet beneath their reef level. In eastern Fiji, 
however, a number of limestone islands, that I believe were formed — 
as atolls, have been sufficiently uplifted and dissected to reveal their 
volcanic platform if it ever existed. In no case is it laid bare; 
hence, as far as these examples go they discountenance the theory. 
I have given details of these islands, taken chiefly from reports by 
Gardiner and Agassiz, in another paper.? There are, on the other 
hand, anumber of uplifted fringing and barrier reefs in Fiji, and also 
I believe in the New Hebrides, the Solomon Islands, the Philip- 
pines, and elsewhere, which rest, as above noted, unconformably on 
the previously eroded slopes of volcanic or other foundations, and in 
which the length of the eroded slope is so great—and I believe it 
may be added, the volume of erosion accomplished in shaping the 
slope is so large—that neither the length of the slope nor the volume 
of the erosion can be reasonably explained as the work of subaérial 
destructive processes while the sea-level was lowered only 40 
1H. E. Crampton, ‘“‘Studies in the Variation, Distribution, and Evolution of the 
Genus Partula.... ,” Carnegie Institution of Washington, 1916, p. 206. 
2“The Structure of High-Standing Atolls,” Proc. Nat. Acad. Sci., IIL (1917), 
473-79- 
