GENERAL ACCOUNT HEDLEY. 13 



they had formerly built.* In general wherever rock appeared on 

 the atoll it was definitely related to the situation. Thus the 

 breccia above described was peculiar to the ocean beach, and was 

 always overlaid by coarse shingle and rough freshly broken coral 

 fragments ; on the leeward shore of the atoll the coral-sand-rock 

 always accompanied stretches of clean sand composed of foramini- 

 fera, coral and molluscan fragments ; again on the lagoon beach 

 of the Funafuti islet there occur low scarps of shingle conglomerate 

 overspread by shingle beaches. 



It would appear, therefore, that these rocks were here con- 

 solidated under the conditions which still prevail. A little 

 excavation with a crowbar shows the surface to be usually 

 harder than the underlying strata. Often an apparently solid 

 crust when overturned exhibited a lower surface bristling with 

 pebbles that adhered to the mass by one end only. The process 

 of consolidation, whether solution by sea water and deposition or 

 not, having operated apparently on the upper surface and to a 

 slight depth only. 



On the outer edge of the reef the surf does not permit much 

 close examination. From the base of the shingle bank or low 

 scarp of breccia, the beach usually stretches seawards for forty or 

 fifty yards in a bare and level expanse, which dries at very low 

 tides in calm weather. It then appears from its Nullipore carpet 

 as a sheet of dull crimson. Moresby noticed this colour on 

 Nanomana Island but erroneously ascribed it to coral. f Deep 

 fissures appear which rapidly widen into crevasses, between which 

 the ground rises into knobs or hillocks, pitted and honeycombed 

 throughout. These breast the surf, beyond them the reef plunges 

 at once into deep water. The coral appears to grow seaward in 

 piers, as these broaden their interstices first form wide trenches, 

 then narrow crevasses that may be stepped across, which clefts 

 tend to be roofed in by growth of Nullipores and are narrowest 

 at the surface, ultimately (proceeding inshore) they become mere 

 fissures and then disappear. This disappearance only refers to 

 the surface, for they probably form tunnels far into the centre of 

 the islet, as shown by the openings through which the sea floods 

 the mangrove swamp. At Nui, the Rev. S. J. Whitmee observed 

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

 reef underneath the islands. In some it bubbles up at the rise 

 of the tide in the midst of the lagoons, forming immense natural 

 fountains."! Further inshore the roof may be broken, and a 



* A formation apparently similar to this breccia is described by Darwin 

 from Keeling Island, and by Chamisso from the Marshall Group. 

 Structure and Distribution of Coral Reefs, 1874, pp. 16 & 34. 



t Moresby New Guinea, 1876, p. 79. 



I In article " Polynesia," Encyc. Britt., (9), xix., 1885, p. 420. 



