176 NATURAL SCIENCE [March 



There is little doubt but each ridge is the result of a single 

 storm. I have already referred in the notice of Atafu in the 

 Tokelau group to a similar ridge of smaller dimensions which 

 was thrown up during the present year, and I have seen several 

 small islands of broken coral and shells which were formed on 

 the reefs in Samoa during the hurricane of a few hours' duration." 



The most remarkable passage which I have read in the literature 

 of these successive hurricane beaches I have spaced in the follow- 

 ing quotation. Describing Maldon Island, an isolated atoll in the 

 Central Pacific, Dixon ^ relates that at some unknown epoch the 

 atoll was inhabited by a colony of Polynesians and was afterwards 

 deserted : he continues : " Opposite all the kitchen heaps along the 

 north and south banks and at some intermediate places, the ridges 

 had been levelled to form pathways to the reef, and flat slabs had 

 been laid down, forming a line of stepping stones. The cuttings 

 and stepping stones extended over the six inner ridges, 

 whilst the three outer ones were invariably as formed by 

 the waves, forming a record at present unreadable of the 

 desertion of the island." 



A geologist will at once seize on tlie fact that here is evidence 

 that the islet has increased by one-third of its breadth since the 

 recent date of the departure of the Polynesians. Further reflection 

 will suggest that a continuation of the process of building line after 

 line of hurricane beaches would encroach upon the reef flat until 

 these beaches reached its seaward edge. Yet the reef flat, by the 

 unanimous testimony of observers, always preserves a given width 

 according to the longitude, or rather, as Dana hints, perhaps accord- 

 ing to the tide of the locality. 



If the facts above adduced be accepted as showing that the 

 hurricane beaches tend to steadily and rapidly broaden the atoll 

 islets to windward, then there is no escape from the deduction that 

 to preserve the normal width of the reef- flat, that too must be 

 steadily growing seaward at the same rate. Presumably the 

 reef flat advances on a talus of its own debris. Some intrinsic 

 evidence in support of the advance is, I think, furnished by the reef 

 flat itself. 



Dana was the first to point out that in the west central Pacific 

 a characteristic feature of the reef flat is the presence of numerous 

 fissures reaching almost to the beach.^ At Nui, Whitmee observed 

 that " the seawater gains access to the central lagoon through the 

 reef underneath the islands. In some it bubbles up in the midst of 

 the lagoons, forming immense natural fountains." ^ Gill, in describ- 



1 W. A. Dixon, Tram. Roy. Soc, K^. W., 1877, p. 175. 



- Dana, " Corals and Coral Islands," 1872, p. 186. 



" In article "Polynesia," Encijcl. Brit. (9) xix., 1885, p. 4'20. 



