292 
APPENDIX II. 
islands in which the volcanic peak has become an eccentiic 
nucleus, from which line after line of barrier-reef has been 
advanced, overlying the volcanic muds ; ’ islands in which 
he did not find the coral limestone of a thickness of 100 
feet. Then we have the upraised atoll, such as Santa 
Anna, which within the small compass of a height of 
470 feet displays the several stages of its growth : ‘ first, 
the originally submerged volcanic peak, then the investing 
soft deposit, and over all the ring of coral limestone, that 
cannot far exceed 150 feet in thickness ; lastly, we come to 
the mountainous islands formed of old volcanic rocks, such 
as St. Christoval, which, although over 4,000 feet in height, 
showed to me no calcareous envelopes at a greater height 
than 500 feet above the sea, the coral limestone crust 
being even thinner than at the smaller and more recent 
islands.’ From these considerations the author concludes 
‘ (1) that these upraised reef masses, whether atoll, barrier- 
reef, or fringing-reef, were formed in a region of elevation ; 
(2) that such upraised reefs are of moderate thickness, 
their virtual measurement not exceeding the limit of the 
depth of the reef-coral zone, i.e. not more than about 150 
feet ; (3) that these upraised reef masses in the majority 
of islands rest on a partially consolidated deposit which 
possesses the characters of the “ volcanic muds ” which 
were found during the * Challenger ’ expedition to be at 
present forming around volcanic islands ; (4) that this 
deposit envelopes anciently submerged volcanic peaks.’ 
The earlier part of the next paper 1 is occupied by a de- 
scription of a reef of the Solomon group and the distribution 
upon it of coral life. According to Mr. Guppy’s observations 
the large masses of corals usually flourish below the wash 
of the breakers, and in these regions corals generally do not 
1 H. B. Guppy. Notes on the Character and Mode of Formation 
of the Coral Beefs of the Solomon Islands. Proc. B. S. Edin. xiii. 
p. 857 (Session 1885-6). 
