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Geology of the Cook Islands
Geology of Cook Islands / From Wikipedia, the free encyclopedia
There are fifteen Cook Islands, all being related to extinct volcanoes that have erupted in the volcanic hotspot highway of the south-central Pacific Ocean. Low islands include six of the more northern islands that are atolls, and four of the more southern being uplifted coral islands. Rarotonga, the largest island of the group is a mountainous volcanic island. Rock formations include late Pliocene to more recent volcanics, Oligocene and Miocene reefs and middle Tertiary limestone underlying atolls[1] More recent emergence of the coral reefs is characterised in several cases consistent with sealevel fall at Mangaia, of at least 1.7 m (5 ft 7 in) in the last 3400 years.[2] The northern Suwarrow Atoll rim has portions of reef dated to between 4680 and 4310 years B.P. and at the northeast of the atoll the three ridges are dated from the land out at 4220 years B.P., 3420 years B.P. and from 1250 years B.P.[2] On Mitiaro the centre of the reef flat has regions dated 5140–3620 years B.P.[2]
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