BY W. G. WOOLNOUGH. 483 



vi. — Summary of Results. 

 The general results may be summarised as follows : — 

 For the most part the coastal portions of the island are com- 

 posed of redistributed tuff (soapstone), interstratified here and 

 there with calcareous formations of comparatively recent geological 

 age, or else of geologically young lavas, tuffs, and agglomerates. 

 These latter also extend throughout the high lands of the interior. 

 At various points in the valleys of the interior there are isolated 

 and, also in some cases, fairly extensive continuous outcrops of 

 rocks enormously older than any of the above. Though such 

 rocks were met with in situ only in comparatively few localities, 

 their distribution must be very wide, as is indicated by their 

 almost universal occurrence in the river gravels. These facts 

 point to the existence of -a general jDlatform of ancient rocks on 

 the surface of which are built up innumerable volcanic cones, 

 whose products as a rule overlap and effectually conceal the 

 underlying rocks. If these older rocks consisted only of plutonic 

 rocks, it might possibly be argued that they represent the deep- 

 seated portions of volcanic mountains which have been so exten- 

 sively denuded as to have their very bases laid bare, in this Avay 

 bringing to light the magma which has solidified there under 

 plutonic conditions. That this is not the case is proved b}'^ the 

 fact that rocks of undoubtedly sedimentary origin, viz., quartzites 

 and slates, also occur, in association with the plutonic rocks. In 

 addition to these, and closely associated with them, there are 

 abundant rocks of volcanic origin whose lithological features 

 indicate that they are of great age. In every character they 

 appear immensely older than the universal andesites. They have 

 undergone extensive molecular rearrangement (showing traces of 

 foliation with development of such minerals as epidote) and 

 decomposition, and are highly jointed, while the comparatively 

 recent tuffs lie uncomformably over them. 



It, therefore, appears that the geological formations of Viti 

 Levu are divisible into two main groups. The first of these 

 includes continental rocks of high but undetermined geological 



