242 DALY. 



rim and the general floor of the lagoon. The total length of the sec- 

 tion, between the outer edges of the main reefs is 55 km. At each end, 

 the width of reef surface within a few meters of sea-level is about 1 km., 

 and the reef surface on the lagoon side plunges rapidly to depths of 

 50 m. or more. The middle part of the section, 50 km. long, has a 

 nearly constant depth of about 75 m., with local soundings of 80-82 m. 

 (the deepest) and 64-66 m. (the shallowest). See also page 194 and 

 Figures 5, 10, 17, 19-22, and 38-43. 



Further, the charts of the Maldives show depths in the main lagoons 

 that are practically identical with those on parts of the same banks 

 or on adjacent banks, where there are no rimming reefs at all (Figs. 

 16-20, 37-43). Examples may be seen in the large-scale charts of the 

 Mlladummadulu and Ari atolls, across which many sections may be 

 run, giving no water deeper than 35 to 55 m., the range of depths being 

 precisely like those between the reef rims where they do exist on the 

 same banks, and like those on the neighboring Malosmadulu and Male 

 atolls. Both the banks rimmed with surface reefs and the banks 

 devoid of such crowns bear occasional "faros" (small atolls) or coral 

 knolls, which have evidently grown up from platforms now 55-80 m. 

 below sea-level. No other banks better show the independent origin 

 of reef and platform. The topographic unconformity "leaps to the 

 eye." To explain it by the subsidence theory, a long pause in sinking 

 is an apparently necessary assumption. Again the submarine physiog- 

 raphy spells crustal stability rather than unrest. 



A related difficulty with the older theory, of no small import, is the 

 absence of main rimming reefs on parts of the banks, which, by hypo- 

 thesis, were formed by long-continued growth of rimming reefs. Two 

 questions arise. Why was the main reef killed? Why were the corals 



Sections illustrating the flatness and shallowness of lagoon floors, their 

 accordance in depth with rimless platforms, the steepness of the slopes flanking 

 both main reefs and knolls, and topographic unconformity between reefs and 

 platforms. 



Figure 38. Tiladummati atoll, through Nekurandu island (Maldive 

 group). 



Figure 39. Mlladummadulu atoll, through Dureadu island (Maldive 

 group). 



Figure 40. Mlladummadulu atoll, through Maswataru island (Maldive 

 group). 



Figure 41. Ari atoll, sectioned south of Well island (Maldive group). 



Figure 42. Longitudinal section, following the main reef of North Malos- 

 madulu atoll, between Duwafuri and Wadu (Maldive group). 



Figure 43. South Male atoll, sectioned north of Mafuri. 



Uniform scales; vertical scale 4 times the horizontal. Water shown in 

 black; rocks, including reefs, are lined. 



