300 
ISLAND LIFE. 
[part II, 
areas of less depth, varying from two hundred to a thousand 
fathoms, and which may therefore indicate the sites of submerged 
islands of considerable extent. When we consider that east 
of New Zealand and New Caledonia, all the larger and loftier 
islands are of volcanic origin, with no trace of any ancient strati- 
MAP OF THE NORTH PACIFIC WITH ITS SUBMERGED BANKS. 
The light tint shows where the sea is less than 1,000 fathoms deep. 
The dark tint „ „ .. more than 1,000 fathoms deep. 
The figures show the depths in fathoms. 
fied rocks (except, perhaps, in the Marquesas, where, according 
to Jules Marcou, granite and gneiss are said to occur) it seems 
probable that the innumerable coral-reefs and atolls, which occur 
in groups on deeply submerged banks, mark the sites of bygone 
volcanic islands, similar to those which now exist, but which, after 
