108 FUNAFUTI 



Radiating from these blocks as from a nucleus are vertical 

 plates of the "blue coral" (Heliopora cocrulea), which 

 extend outwards, branching as they go, for a distance of 

 3 yards or more. Overlapping the reef lies a layer of 

 consolidated coral breccia ; it has suffered much from 

 erosion by the sea, and bounds the inner side of the 

 depression in cliffs 3 or 4 feet in height. A sheet of 

 clear green water covers the swamp ,at high tide, con- 

 verting it into a shallow lake, which as the tide falls 

 empties itself through deep holes in the floor into subter- 

 ranean passages, which freely communicate with the 

 outer sea. The northern end of this depression is closed 

 by coral breccia, and overgrown with mangroves ; but 

 farther on it recommences and extends through the 



o 



remainder of the island, almost as far as its northern- 

 most extremity, forming a discontinuous narrow trough 

 bordered by steep cliffs. This trough, and the depression 

 to which it belongs, owes its origin in some degree to 

 solution by sea-water. 



We have deviated from our walk across the island to 

 follow the course of its central depression, let us now 

 return and resume our traverse. The blackened frag- 

 ments of coral, resembling nothing so much as the 

 clinkers of lava which cumber the slopes of Etna, con- 

 tinue seawards, and are loosely piled to form a gently- 

 rising ascent ; so loosely piled that they often topple over 

 at a touch, and afford very uncertain or even dangerous 

 foothold. 



Walking circumspectly, therefore, up the slope we soon 

 reach the summit of a long ridge, and find ourselves 

 looking towards the Andes, some thousands of miles 



to this conclusion from evidence furnished by the " dead reef '' of 

 the mangrove swamp, by the " sea-stacks," or pinnacles of coral-rag 

 of the tidal-platform, and by the steep cliffs which in some of the 

 islets border the lagoon. 



