Almost-atoll of Aitutaki: reef studies in the Cook Islands, South Pacific

Rarotonga and Aitutaki form the summits of separate
volcanic masses rising from depths of 4000 m, at which depth
the cones are 45-55 km in diameter (Summerhayes and Kibblewh
1966, 1967).The lower slopes of the cones average 15-25
increasing to 30 in the upper 750 m and becoming very steep
the surface reef is approached. The Mauke-Aitutaki line of
islands is thought to be of early Tertiary age: the surface
volcanics are much eroded, with a subdued topography, or are
capped with limestones (Wood, 1967; Wood and Hay, 1970). On
Rarotonga, where the relief is much stronger (maximum altitude
640 m), radiometric ages of 2.3-2.8 million years date the 1
as Pliocene (Tarling, 1967). Mangaia, with a cap of Oligoce
Miocene limestones, must be much older (Marshall, 1927). Evi
dence from the deep-sea drilling programme indicates that th
ocean floor in the area of the southern Cooks is Paleogene
(22.5-65 million years) in age (Winterer, 1973), thus provid
a maximum age for the islands. It is probable that the gross
history of the Cooks resembles that of other, better-known
reef-capped Pacific volcanic cones known to have been initia
in the early Tertiary.

Available online

Call Number: [EL]

Physical Description: 235 p.