200 



^ALP.ATROSS" TROPICAL PACIFIC EXPEDITION. 



Passage) is a cailon cut through the limestone rocks, deeply undercut on 

 one side, the sides of which are perlu^ps 200 feet high (Pis. 123, 219). 



The vegetation which comes down to the water's edge on the faces of 

 this deep inlet of Neiafu is very luxuriant (PI. 123). In every direction 

 are large trees covered with vines, and the vegetation is perhaps as fine 

 as any we have seen in the Southern Pacific. The canons in Vavau 

 resemble those of Ngillangillah in Fiji, only they are on a much larger scale. 

 The vertical cliffs of the sound to the south of Neiafu, and all the cliffs we 

 have examined, are full of caverns indicating former lines of sea level. The 



caverns near low-water mark are used by 

 the natives as boat-houses. The excellent 

 chart of Vavau,^ from the surveys of Cap- 

 tain Field, gives us the means not only 

 of following the changes which have 

 taken place in the topography of the 

 group, but also of tracing the manner in 

 which they have been brought about 

 (PI. 219). The bars and islands indicate 

 old connections, and are now represented 

 by reef flats. The cuts which have been 

 made across the narrow parts of the land, 

 like the cut at the south end of Neiafu 

 harbor, are due to the gradual wearing 

 away of the original land (PI. 219). 



It is interesting to note the similarity of the results of denudation and 

 erosion of Nomuka and of Vavau. The sinks of Hunga, of Ano (PI. 219), 

 are similar to the sink of Nomuka. The horseshoe-shape of that island 

 corresponds to the ridges which enclose the sinks of the former island. A 

 similar denudation and erosion, together with the solution and disintegration 

 of the enclosed limestone, only carried on on a larger scale, gives us the 

 explanation of the formation of such basins as those to the south of Tofoa, 

 to that of Nua Papu, to the sink separating Pangai and Otungake (PI. 219), 

 to the bays south of Pangai, the dry sink to the north of Koloa. the 



1 A Chart 3098. 



En TK A. NCI' 



