106 THE CORAL REEFS OF THE MALDIVES. 



to have been formed by the coalescence of smaller faros or patches, once 

 separated by comparatively shallow water. The depth of the passes be- 

 tween the faros of the west face of Ari is not as great as on the eastern, 

 where the average depth of the narrow passes is fully twenty-four fathoms. 

 On the western face are several passes with not more than from six to fifteen 

 fathoms. The lagoons of the faros of the west face of Ari are many of them 

 quite deep ; ten, fourteen, fifteen, sixteen fathoms are the depths indicated 

 on the charts. These faros are also characterized by the great width of the 

 western rim flats of the lagoons. Throughout the southern part of Ari are 

 a number of small and incipient faros in all stages of development. On 

 the little island which divides the second southern pass on the west face of 

 Ari, the small reef flat is covered with great slabs of beach rock.^ 



About five miles to the southeast of Mandu Faro and about three miles 

 and a half south of Furadu, is a large elliptical ring over two miles in length 

 (PI. 57, fig. 1), with a fairly wooded island on the southern rim flat and a 

 small sand bank on the western face of the rim, which is nearly all awash. 



The faros in this part of Ari have been somewhat modified since they 

 were surveyed by Captain Moresby. On the rims of several we find islets 

 and islands, or sand-bars and banks, which did not exist at the time of the 

 survey. The changes in this part of the group may be due to the position 

 of the faros exposed to the action of the northeast and specially the south- 

 west monsoon in that area of Ari. The existence of the lines of boulders 

 on the outer rims of the faros of the southern and western faces of Ari shows 

 the extent of the action of the southwest monsoon on the faces of the 

 faros exposed to them. 



About a mile and a half south of Furadu there is a circular faro 

 (PI. 57, fig. 2) fully a mile in diameter with a lagoon evidently deepest at 

 the eastern extremity, where it is of a dark blue color, and shallower, of a 

 greenish-blue tint, towards the western end. The lagoon is surrounded by a 

 wide greenish rim of uniform width, flanked with fine patches of corals on 



1 Gardiner {loc. cit., p. 341) has given an excellent account of the formation of terraces of beach 

 sandstone, off a sand beach ; sandstone beach rock is not necessarily, as is stated by him (loc. cit., p. 342), 

 formed on a beach, to a large extent protected from the heavy ocean rollers, or the waves within a 

 lagoon. Among other cases in the Pacific coral reefs (Mem. Mus. Comp. Zool., Vol. XXVIIL) where 

 this is not the case, I might mention especially the beach rock on the east face of Nanuku Levu in Fiji 

 (PI. 106, A. Agassiz, Bull. M. C. Z., XXXIII.). 



