410 THE GEOLOGY OF THE NEW HEBRIDES, 



axis in a more or less east and west direction, from which several 

 lesser ridges branch off to the south; the razorbacks are highest 

 at the north-east corner of the island, culminating in Mt. 

 Macdonald, 2203 ft. 



Briefly summarised, the geological features are, — a base of 

 andesite pumice tuff overlaid by thick beds of submarine tuff, 

 varying in texture from coarse to much finer-grained types, some 

 of which cannot be distinguished from Fiji Soapstone. Later 

 basic eruptions have affected the N.E. corner of the island, 

 producing thick beds of agglomerate. Superimposed on this 

 foundation and arranged in terrace-formation to a height of 

 quite 2000 ft., is a thin veneer of coral reef -material, which, from 

 its extensive lateral development, has given rise to the popular 

 notion that Efate is entirely composed of coral limestone. 



The small islands of Mau, Nguna, and Pele are practically 

 wholly volcanic, resulting from a continuation of the agglomerate, 

 forming basic eruptions of the mainland. Moso, Leleppa, and 

 Erradaka are built up of coral limestone on a foundation of fine 

 submarine tuffs. 



Mataso is a small island lying 10 miles N.N.E. of Nguna, and 

 has been described by Lieut. Frederick as consisting of two 

 distinct hills joined by a low beach of sand and coral. The 

 higher of the two hills is a remarkable peak 1669 ft. in height, 

 and only 1870 yds. long by 1000 yds. broad. The lower hill is 

 485 ft. high. The whole island is, he says, of volcanic origin; a 

 narrow fringing reef is, however, growing at present on either 

 side of the island (Plate xvi., fig.l). 



Monument Rock. — A precipitous pyramid rising vertically 

 from the sea 1 mile E. of Mataso, is described by the same 

 authority as being 422 ft. high and 130 yds. in diameter at the 

 base; although a landing could not be effected for the purpose of 

 collecting specimens, yet he states it is evidently wholly 

 composed of volcanic rock. 



Makura is situated 6 miles north of Mataso, and is just one 

 mile in length. It is of volcanic origin, rising up in the form of 



