PRESIDENTIAL ADDRESS. 37 
indicate strongly that at times, during submergence, the 
corals grew luxuriantly. The lines of marine erosion, 
and the narrow benches of erosion on the raised reefs 
themselves, as seen so well on Makatea, Vatu Lele, and 
Walpole Island, suggest most strongly that coral growths 
were checked, during the last great vibratory elevation or 
warping of the island, and that this corresponds, apparently, 
with a period or with periods of cold. 
Summary. 
Corals grew in the Pacific during Tertiary and Pleisto- 
cene time, and they appear to have been formed on sinking 
‘surfaces of erosion. 
The Tertiary forms are well bedded and are those of 
transportation in the main. They are not typical coral 
reefs, but were formed with the outwash, within tectonic 
troughs, of associated highlands. These troughs were 
relatively shallow. 
The Pleistocene types are not bedded and are due to 
the growth of coral in situ on sinking surfaces of erosion 
in clear water. 
These Pleistocene reefs were developed mainly to the 
east of the more stable islands and they were elevated in 
part ata later date, to form raised coral reefs, while other 
portions sank progressively and became large atolls. 
While the smaller islands were moving upward and 
downward in the form of undulations, the larger islands 
forming the west of each main group were in stable equi- 
librium and wide benches or platforms of marine erosion 
were formed around them. 
A recent submergence of the whole of the Pacific area 
to the extent of 200 feet approximately, allowed the form- 
ation of great fringing reefs to the smaller islands, and of 
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