EQUATORIAL POLYNESIA. 473 



zone of plains encircling the island with a fringe of verdure about two miles deep ; 

 the deposits are prevented from being carried seawards by an outer barrier of reefs. 



The Manahiki islets, scattered to the north-west of Tahiti, are all " low," like 

 those of the great archipelago specially designated by that name. This Low 

 Archipelago, formerly known as Pomotu ("Lands of Night" or "Mystery"), 

 and at present as Tuamotu ("Remote Lands "), might well have retained the 

 name of " Dangerous " given to it by Bougainville. Nearly all the visible islets 

 are atolls or mere reefs extremely perilous to navigators. Before the introduction 

 of the cocoanut the only arborescent plants were the pandanus and a species of 

 box called mikimiki. Of the 78 islets composing the archipelago properlj^ so 

 called 74 appear to be under 14 feet high, and the few that attain an eminence 

 of 120 feet look like veritable mountains. Possessing no lagoons of smooth water 

 they are avoided by skippers The atolls are generally of a regular oval shape 

 disposed in the direction of the archipelago itself, that is, north-west and south- 

 east. 



South-east of Tuamotu the relatively large inland of Mangareva forms with a 

 few elevated islets a distinct volcanic group, known as the Gambier Archipelago, 

 and memorable in connection with the researches of Darwin on the oscillations of 

 the terrestrial crust. The whole group is enveloped in an outer coral reef appa- 

 rently indicating the ancient coastline of now submerged land, which, according 

 to the illustrious naturalist, slowly subsided, while the exterior rim was kept near 

 the surface by the coral builders. But whatever is to be said of this theory, which 

 has recently been contested by Guppy, Murray, and others, it is certain that 

 Gambier consists essentially of an igneous nucleus round which the polyps have 

 raised their coral structures. DufE, the central eminence (1,200 feet), is an extinct 

 volcano, as are all the other heights scattered over the inner waters. 



Apart from a few atolls and coral reefs the Marquesas are all old volcanoes, or 

 groups of volcanoes, probably extinct for many ages, and no longer anywhere pre- 

 senting the regular form of cones with terminal craters and lava sheets. Nuka- 

 hiva, largest member of the archipelago, shows on its west side nothing but steep 

 cliffs and stony plateaux almost destitute of vegetation ; but the central part, source 

 of the largest stream, is enclosed by a circle of hills culminating in a peak 3,860 

 feet high. Hiva-oa has better preserved its primitive architecture, still forming 

 an amphitheatre of volcanic hills, one of which is the highest point in the archi- 

 pelago (4,140 feet). 



The solitary Easter Island, on the eastern verge of Polynesia, is a huge block 

 of lava, terminating in a volcano ruptured at the three corners of its triangular 

 mass. The highest summit at the north-west angle rises 1,640 feet sheer above the 

 surface of the water. 



Climate. — Flora. — Fauna. 



Equatorial Polynesia is almost entirely comprised within the zone of the south- 

 east trade winds, the groups north of the equator being alone exposed to north- 

 east breezes, which in summer veer roimd to the north-west, or become variable 



