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APPENDIX II. 
indicated by the broad reefs, barrier islands, and atolls 
of the Feejee groups. 
Elevation undoubtedly has occurred in several localities, 
e.g. in the Austral, Hervey, Friendly, and even in the 
Sandwich Islands, but in all the amount is small — not, so 
far as he knows, anywhere exceeding 300 feet. These Pro- 
fessor Dana considers to be merely local phenomena, and he 
passes in review several facts showing the uncertainty of 
evidence as to little or no subsidence, or as to recent ele- 
vation from narrow reefs and the volcanic character of 
islands. Further, these local elevations in coral seas, 
where they do occur, are spread over very large areas. For 
instance, the Paumotu Archipelago, consisting of more than 
eighty atolls and two barrier islands, contains only three 
or four atolls that are over 12 feet high. Of these Metia 
is 250 feet high. Dean’s, probably at its highest 15 or 20 
feet, is 60 miles to the N.N.E.; far to the S.E. of that, 
nearly 1,450 miles from Metia, is Elizabeth Island, 80 feet. 
‘ Locate these points on a comment, and Pacific distances 
and the length of Pacific chains of atolls will be appre- 
ciated.’ 
Professor Dana next reviews the arguments in favour 
of hypotheses other than that of subsidence, and deals with 
the soundings of the ‘ Challenger ’ off Northern Tahiti, upon 
which great stress has been laid by Mr. Murray and others. 
Here, from the edge of the barrier reef, the sea bottom, 
covered partly with growing corals, deepened gradually in 
about 250 yards to 40 fathoms (i.e. to considerably below 
the depth at which reef-building corals usually can grow), 
then from this limit the bottom dropped down in about 
100 yards to 100 fathoms ; at first precipitately at an angle 
of 75°, then more gradually, but above 45° ; and for 
another 150 yards the sea bed still shelved down at 30°, 
but beyond this the slope diminished in the course of a 
mile to 6°, where at last the depth was 590 fathoms. 
