THE NOMUKA GROUP. 193 



shore at Nomuka Iki (PI. 216), found the soutliern peak (147 feet high) 

 made up of volcanic material very similar to the Fiji soapstone, but some- 

 what darker. An elevated ledge of old coralliferous limestone runs on the 

 south side of the west end, and a high sand beach faces the northern line 

 of the shore. From the southeastern point sand keys extend, forming a 

 flat of considerable extent. 



The eastern part of the island of Nomuka is occupied by a large lagoon, 

 which has been separated from the sea by a high sand beach thrown up 

 between the southern extremities of the two limestone ranges forming 

 the western and eastern faces of the island (Pis. 119, 216). The island 

 must formerly have been more or less horseshoe-shaped, its faces enclosing 

 a sound formed by denudation and erosion and the inroads of the sea, much as 

 the sounds in the Bermudas and elsewhere have been formed. The lagoon 

 is not more than four to five feet deep, and occupies the shallow sink enclosed 

 between the two main ridges of Nomuka. Yet such a lagoon if surrounded 

 by a low land rim would be looked upon as an excellent specimen of 

 a subsidence atoll ! The slopes from the outer ridges toward the central 

 basin are slopes of denudation ; here and there are huge spurs covered with 

 vegetation, running out as buttresses on the flanks of the rim (PI. 119, 

 fig. 1), a very different structure from that found in any atoll we have 

 examined ; this can only be accounted for by the difference in the extent 

 of denudation and erosion, which has taken place in different parts of 

 this basin, according to the density and more or less friable nature of the 

 calcareous limestone of the outer ridges. The buttresses remind us of 

 similar buttresses in the sink of Kambara ; they are in marked contrast 

 with the comparatively bare volcanic slopes of Nomuka Iki, and other 

 volcanic islets in the vicinity. A number of salt-water fishes are found in 

 the lagoon. 



Koto Maka and the western part of Nomuka were examined by Dr. 

 Mayer, who found it to consist of elevated coralliferous limestone, much of 

 it changed to hard calcite, and containing numerous fossils near its base. 

 I examined, myself, the ridge to the east of the lagoon, as well as the shores 

 of the lagoon itself, and found the highest point of the eastern ridge of the 

 lagoon to consist of calcite, and of elevated coralliferous limestone from 



