AGASSIZ: FIJI ISLANDS AND CORAL REEFS. a 
outer edge upon which corals may flourish and spread seaward, when 
the talus has reached the depth at which corals can grow. I am in- 
clined to think that the examination of such a reef will alone give us 
an idea of the way in which such thick masses of coralliferous lime- 
stones were formed, —— most probably by a combination of subsidence, 
of accretion, and of lateral expansion. 
What the exact age of the elevated limestones is, I am as yet unable 
to state. Their aspect and position show them to be of considerable 
age, and probably antecedent to the present period, and in many ways 
they resemble some of the late tertiary elevated limestones I have found 
on the north coast of Cuba. The great thickness which the elevated 
coralliferous limestones attain in this group, at least 800 feet, also 
shows that it may have been deposited during a period of subsidence, 
but not a period of subsidence in our epoch, or which could have had 
any effect in shaping the outline of the islands of the Fiji and their 
accompanying reefs, 
Whether the elevation of the Fiji group corresponds in time with that 
of the northern part of Queensland, Iam unable to state. I can only 
suggest that it is not improbable that the elevation of Queensland and 
of the islands to the east of the Solomon, New Hebrides, etc., including 
the Fijis and Samoa, may have been synchronous, and that these islands 
have, like northern Queensland, been subject to an immense denudation 
and erosion, reducing them to their present proportions. The elevation 
haying probably, as in northern Australia, been preceded in still earlier 
geological times by a great depression, during which the thick beds of 
coralliferous limestone may have been formed. Judging from some pho- 
tographs I have seen, I should feel inclined to consider the atolls of the 
Paumotus to have been formed by causes similar to those which have 
shaped those of the Fijis. 
The Tonga Islands as described by Lister! are arranged by him in 
three divisions: (a) purely volcanic islands; (0) islands formed of 
volcanic materials laid out beneath the sea and since elevated, with or 
without a covering of reef limestones; and (ce) islands formed entirely of 
reef limestones. 
The islands of the Vavan group consist entirely of limestone, the for- 
mation of which must have been at least 300 feet thick. The islands are 
flat-topped, and the majority stand at one of three levels of elevation. 
Lister? figures the terraces of the islands to the south of Vavau. At 
1 Notes on the Geology of the Tonga Islands. By J. J. Lister. Q. J. Geol. 
Soe. of London, Vol. XLVII. p. 590, 1891. 
2 Loc cit., p. 608. 
