OF THE TONGA ISLANDS. 007 



arms of the sea. The islets are grouped ahout this coast, in some 

 casics continuing the lines of the ])r()in()ntories. The hcjintiful and 

 secluded harbour of Neiafii is hounded in part by two of these pro- 

 montories, and protected from the sea by one of the larger islets 

 situated between them. It forms a long basin more than 20 fathoms 

 deep over the greater part, and almost entirely surrounded by land 

 over 100 feet in height. 



The surface rock all over the group consists, so far as I am aware, 

 of limestone. I was unable to lincl the underlying basis at any 

 point. Even at the foot of the high clifl's on the northern shore the 

 rock, at the two points at which I saw it, was of this nature, and I- 

 found no fragments of volcanic or any other formation than lime- 

 stone on the beaches. Although I saw no vertical cliff at this part 

 of the island, extending from the top to the shore, the coast-line is 

 in many places so steep that I have no doubt that the formation 

 attains a thickness of at least 300 feet. It consisted for the most 

 part of a hard homogeneous material, but at one point, in the lower 

 part of the cliff, numbers of large bivalve shells were embedded. 



The main mass of the island presents an undulating surface, 

 gradually sloping from the high northern border towards the south. 

 Though there are valley-like depressions in several places, I came 

 upon none which contained streams or even ravines. Springs of 

 fresh water issue from the rock at many points on the shore. 



The outlying islands to the south of the group, as may be seen by 

 the Admiralt}' chart (jS^o. 2357), are surrounded by coral-reefs, which 

 in many cases extend as broad expanses far from the island with 

 which they are connected. As the inlets penetrate among the islands 

 and promontories, and their shores are cut off from the open ocean, 

 the reefs become narrower or disappear ; though in some cases (as in 

 the inlet to the north of the promontory in which Neiafu is situated) 

 there are coral reefs of considerable extent growing far up in the 

 sheltered channels. 



There is one feature which at once strikes a visitor approaching 

 the group by the usual steamboat course from the south-west and 

 passing up to the harbour of Keiafu, namely, that the off-lying 

 islands and projecting points of the main island, on either hand, are 

 flat-topped when seen in profile, and that the majority of them 

 stand approximately at one of three levels of elevation above the 

 sea. Corresponding in level wath the tops of the lower islands there 

 are, moreover, terraces on the sides of the intermediate and highest 

 ones ; and in the same way there are, on the sides of the highest 

 points of land, terraces whose level corresponds with the tops of the 

 islands of an intermediate height. 



The islands and promontories may thus be described as being one-, 

 two-, or three-storied (see fig. 3). 



On first entering the group, the flat one-storied islands Hunga 

 and Nuipapa lie on either hand : their sides drop vertically into the 

 sea and are deeply undermined below by the action of the waves. 

 Kight ahead stands up the mass of Mo'uuga Lafa ( = Flat Mountain), 

 whose densely wooded sides present two well-marked terraces in 



