144 



PROCEEDINGS OF SECTION C. 



a very definite statement, and the basis upon which the classification 

 as tertiary rests should certainly be stated, for it appears from the 

 Funafuti Report that the greatest care has to be exercised to dis- 

 tinguish whether such limestone is recent or not. In particular, 

 some of the tertiary limestone from the Paumotus should have been 

 closely examined, or if this was done a definite statement of the 

 reasons for classing it as tertiary would have been most interesting. 



The Cook Group was not visited by Darwin and Aitutaki was 

 the only island visited by Agassiz. The following extracts give his 

 views in regard to that island : — 



Aitutaki. — "There are a number of volcanic negroheads on 

 the flats. This group is an excellent example of a volcanic rock 

 fiat upon which corals are growing. The formation of the under- 

 lying base can be traced, as volcanic outliers crop out at many 

 places on the barrier reef." — Agassiz, loc. cU., p. xvii. 



Kangiamotia 650 ff 



Raised Barrier Reef 



Present Rtet 







Fig. 4. 

 Section across Western part of Mangaia Island. 



The Cook Archipelago. — " The elevated islands have narrow 

 reef-fiat platforms formed by submarine erosion." 



I was not able to visit Aitutaki, but did go to Rarotonga and 

 Mangaia. Raratonga has a fringing reef which at the south end is 

 nearly a mile distant from the coast. (PI. XI,, Fig. 3.) This wide 

 reef platform here contains some spots a few fathoms deep, but 

 there is no lagoon comparable with those in the Society Group. 

 There is raised coral 10 feet above sea level at many places on the 

 coast of this island, notably at Ngatangiia, and between this 

 raised coral and the volcanic rock is a sw^amp that may mark an 

 earlier lagoon. (PL XI.. Fig. 4). 



Mangaia is of great interest. Here there is a well-developed 

 marine erosion surface forming the summit of the island 650 feet 

 above sea level. An alluvial flat a few feet abo^•e sea level separates 



