| ELEVATIONS IN PACIFIC CORAL REGIONS. 373 
With regard to the other islands of these groups, Manuai, 
Aitutaki, Rarotonga, Rimetara, Tubuar, and Rawavai, the de- 
scriptions by Williams and Ellis appear to show that they have 
undergone no recent elevation. 
é Tonga or Friendly Islands, and others in their vicinity. 
All the islands of the Tonga group about which there are 
reefs, give evidence‘of elevation: Tongatabu and the Hapait 
islands consist solely of coral, and are elevated atolls. 
Hua, at the south extremity of the line, has an undulated 
mostly grassy surface, in some parts eight hundred feet in 
height. Around the shores, as was seen by us from shipboard, 
there is an elevated layer of coral reef-rock, twenty feet thick, 
worn out into caverns, and with many spout-holes. Between 
the southern shores and the highest part of the island, we ob- 
served three distinct terraces. Coral is said to occur at a height 
of three hundred feet. From the appearance of the land, we 
judged that the interior was basaltic ; but nothing positive was 
ascertained with regard to it. 
Tongatabu (an island visited by us) lies near Eua, and is in 
some parts fifty or sixty feet high, though in general but twen- 
ty feet. It has a shallow lagoon, into which there are two en- 
trances ; some hummocks of coral reef-rock stand eight feet out 
of water. 
Namuka and most of the Hapazi cluster, are stated by Cook 
to have abrupt limestone shores, ten to twenty feet in height. 
Namuka has a lagoon or salt lake at centre, one and a half miles 
broad; and there is a coral rock in one part twenty-five feet 
high. It is described by Williams, p. 296. 
Vavau, the northern of the Group, according to Williams 
(p. 427), is a cluster of elevated islands of coral limestone, 
thirty to one hundred feet in height, having precipitous cliffs, 
with many excavations along the coast. 
