Reviews—Dr. H. B. Guppy’s Geology of Solomon Islands. 169 
appear to be of more recent volcanic origin. It seems to be formed 
of a linear series of lofty mountain cones, one of which at least is 
active at the present day. The smaller islands of volcanic consti- 
tution are either mixtures of modern rocks with more ancient and 
often highly erystalline rocks, or they are composed almost entirely 
of recently erupted material. In the latter case the islands preserve 
the volcanic profile, possess craters, and sometimes exhibit signs of 
latent activity. Pages 8-62 are devoted to the details of these 
volcanic islands. 
That an enormous amount of denudation has affected the Solomon 
Islands is evident from the laying bare of the deep-seated plutonic 
rocks before mentioned ; and it is also equally certain that this is an 
area of elevation, by no means remote in time, through a vertical 
range of some thousands of feet. This is abundantly shown by the 
various muds and oozes of deep-sea type which now constitute a 
notable proportion of the land above sea-level—a class of deposit 
possessing considerable interest for geologists, whilst to those who 
have been engaged in testing the nature of the ocean floor such rocks 
afford an opportunity of a comparison of great value. Hitherto 
there has been little chance of studying the consolidated oceanic 
muds, since it is pretty well understood by this time that the 
ordinary formations of continents and continental islands, such as 
our own, have nothing in common with the oceanic muds and oozes 
now in course of deposition. It is just possible that the Chalk may 
be an exception to this rule, but at any rate we have quite enough 
controversial matter before us without troubling ourselves with this 
question. The so-called “chalk” of New Ireland is regarded by 
Mr. Brady as a deep-sea deposit of comparatively recent age, which 
was probably formed in depths of not less than from 1500 to 2000 
fathoms. Then again there is the well-known Suva deposit, or so- 
called “soapstone ” of the Fiji Islands, which has been the subject 
of a recent communication by Mr. Brady to the Geological Society. 
Thus glimpses have from time to time been obtained of the nature 
of the deep-sea deposits, when elevated into dry land, from more 
than one quarter, and we are therefore prepared to read Mr. 
Guppy’s account of the recent calcareous formations of the Solomon 
Islands with a considerable amount of interest, not to say of 
curiosity. 
The recent rocks, he says, may be arranged into several groups, 
commencing with the coral limestone and ending with the deeper 
deposits. The first group includes the coral limestones properly 
so called, which are mainly composed of the massive corals, in 
different stages of fossilization. The interstices are filled by coral 
débris, molluscan shells, and the remains of the numerous organisms 
that live upon the reefs. 
The second group includes those coral limestones which have the 
composition of the coral muds and sands that were found by the 
“Challenger” expedition to be at present forming near coral islands 
and along shores fringed by coral reefs. They are derived chiefly 
from the disintegration of the neighbouring reefs, but they receive 
