FORMATION OF CONTINENTS

Press, Volume CI, Issue 29860, 28 June 1962, Page 11

FORMATION OF CONTINENTS

N.Z. Geophysicist’s Study A study in the formation of continents is being carried out by Mr W. I. Reilly, of the Geophysical Survey of the Department of Scientific and Industrial Research. His recent work indicates, he says, that Fiji is probably a continent in the first stages of formation, in contrast to other island groups Which are only volcanic deposits in the ocean floor. New Zealand is continental he believes. On Friday, Mr Reilly will leave Auckland to make a comprehensive gravity and magnetic survey of two atolls —Ataful, in the Tokelaus, and Manihiki, in the northern Cook Islands, to gain further information about the geophysical structure of oceanic islands and the neighbouring ocean bed. In particular, he wants to try to elucidate whether the sinking of a volcanic island—attested by its survival only as a coral atoll —is caused mainly by the subsidence of the ocean floor or by the gravitational spreading of the material of the island.

During .April and May. Mr Reilly carried out reconnaissance gravity surveys on Penrhyn, Manihiki, and Fak. aofu, in the Tokelaus, and Nukunono and Atafu, in the northern Cooks, on Savai’i, in Western Samoa, on Tutuila at the invitation of the Government of American Samoa, and on Vanua Levu at the invitation of the Government of Fiji. He also made new ground observations on Upolu, in Western Samoa, and made a gravity traverse through the middle of Viti Levu. in Fiji. Mr Reilly is particularly interested in getting information which will indicate at what stage in the growth of a volcanic island the weight of the deposits will cause the earth’s crust to yield and so create a continental-type base to the island.