Chatham Rise

The Chatham Rise is an area of ocean floor to the east of New Zealand, forming part of the Zealandia continent. It stretches for some 1,000 kilometres (620 mi) from near the South Island in the west, to the Chatham Islands in the east. It is New Zealand's most productive and important fishing ground, as well as important habitat for whales.

Relative to the rest of the Pacific Ocean waters around New Zealand, the Chatham Rise is relatively shallow, no more than 1,000 metres (3,300 ft) deep at any point. This shallowness is made more remarkable by the depth of the ocean immediately to the north and south. To the northeast, the Hikurangi Trench, an extension of the much deeper Kermadec Trench, drops to below 3,000 m (9,800 ft) close to the New Zealand coast, and further from the coast the Rise borders on the Hikurangi Plateau. To the south, similar depths are achieved in the Bounty Trough. Past the eastern end of the rise, the sea floor drops away to the abyssal plain.

Geologically and tectonically, the Chatham Rise can be thought of as an extension of the eastern South Island. It was largely dry land at the end of the Cretaceous (66 million years ago) and formed a large peninsula extending from New Zealand to the Chatham Islands at that time.

The Cretaceous landscape of the Chatham Rise was characterized by a volcanic landscape. Fossils found on the Chatham Islands characterize the flora and fauna of the Chatham Rise in the late Mesozoic. The region had forests dominated by gymnosperms (such as Araucaria, Mataia and Podocarpus) and Lycopodiopsida (clubmosses). Some angiosperms were also present. Dinosaurs such as theropods dwelt on the peninsula and probably evolved into numerous endemic forms (Stilwell et al. 2006).

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