Macauley Island is a volcanic island in New Zealand's Kermadec Islands, approximately halfway between North Island of New Zealand and Tonga, in the south-west Pacific Ocean. It is part of a larger submarine volcano that features a 10.5-by-7-kilometre (6.5 by 4.3 mi) wide underwater caldera northwest of Macauley Island. Two islets, Haszard Island and Newcome Rock, lie east offshore of Macauley Island. The island is mostly surrounded by high cliffs that make it difficult to access; the inland parts are mostly gently sloping terrain covered with ferns and grasses. The island formed during several volcanic episodes that produced mainly basaltic rocks as lava flows. During the Holocene, a large explosive eruption produced the Sandy Bay Tephra; this eruption may have had a volume of more than 100 cubic kilometres (24 cu mi) and the Macauley caldera might have formed during that occasion. Later, most of the current surface of Macauley Island formed as the Haszard Formation. Two possible eruptions took place during the 19th century offshore Macauley Island; a hydrothermal vent system is active at Macauley Cone in the caldera. Macauley Island is an important breeding place for many seabirds, which come on land only to reproduce. The island is uninhabited but Polynesians and, during the 19th century, whalers introduced goats, pigs and rats which damaged the island's ecosystem. During the 20th and 21st centuries these invasive species were largely eradicated, leading to a recovery of the previous vegetation. The island is part of several protected areas.
History Macauley Island was first seen by Westerners on 30 June 1788 aboard the Lady Penrhyn. It is likely that Polynesians visited the island during or after 1300 despite the lack of direct archaeological evidence other than a flake made out of obsidian discovered in 2015. They may have obtained obsidian from the island. The island was originally named Macaulay after George Mackenzie McCaulay, an alderman of the City of London who had contracted the voyage of the Lady Penrhyn. A castaway depot was established on the north-eastern side of Macauley Island in 1888. Macauley Island and other Kermadec Islands have been part of New Zealand's territory since the 19th century. Early explorers envisaged planting trees on Macauley Island and using the Kermadec islands as places to settle from New Zealand. In 1957, the Kermadec Islands were briefly considered as a potential testing ground for the British nuclear weapons programme but were ruled out for logistical and political reasons. Archaeological excavations were conducted in 1990 on Macauley and Raoul Island.
Geography and geomorphology Macauley Island is in the Kermadec Islands, 109 kilometres (68 mi) south-south-west of Raoul Island and roughly halfway between Tonga and New Zealand. Cheeseman Island and Curtis Island lie south-south-west of Macauley Island, and Havre and L'Esperance Rock are even farther south; together these islands form the southern group of the Kermadec Islands, of which Macauley Island is the largest. Raoul is visible from Macauley Island when the weather is clear. Located within the exclusive economic zone of New Zealand, the islands are since 1990 within the Kermadec Islands Marine Reserve and the Kermadec Benthic Protected Area administered by the New Zealand Department of Conservation. The islands are, with the exception of the weather station on Raoul Island, uninhabited.
The volcano rises from a depth of 1,700 metres (5,600 ft) where it is 23–30 kilometres (14–19 mi) wide; it is elongated in east-southeast direction and features a 10.5 by 7 kilometres (6.5 mi × 4.3 mi) wide submarine caldera northwest of Macauley Island. The caldera floor and rim are 1,100 metres (3,600 ft) and 600 metres (2,000 ft) below sea level, respectively. The caldera is elongated in east-north-east direction and features north-north-east trending lineaments that extend to Macauley Island. Jumbled blocks, presumably from landslides or slumps, cover the portions of the caldera adjacent to Macauley Island, and there is evidence of collapses on the western caldera margin. A fault runs inside the caldera next to its southeastern margin. The caldera floor is covered with pumice, and thick pumice deposits exist on the flanks of Macauley volcano.North-northwest of the caldera is a 9-kilometre (5.6 mi) long structure called Lloyd dome or Curtis Ridge; it is surmounted by a lineament of cones that rise to 80 metres (260 ft) below sea level. 300-metre (980 ft) high and 700-metre (2,300 ft) wide Macauley Cone is located on the southeastern caldera margin and rises to 250 metres (820 ft) depth. It is capped by an 80-metre (260 ft) wide and 45-metre (148 ft) deep crater with a floor covered with ash and sulfur, and its slopes are covered with talus. Parasitic vents and structures have been identified on the caldera rim and submarine slopes of Macauley Island volcano during bathymetric analysis, some of which are the source of lava flows that extend into the caldera and down the flanks. The seafloor on the slopes of Macauley volcano is covered with sand, rock, breccia and bacterial mats. "Sediment waves" up to 1 kilometre (0.62 mi) long and 100 metres (330 ft) wide occur on the submarine slopes and extend over 55 kilometres (34 mi) away from the volcano. These waves appear to have formed in part during sector collapses and in part during density flows triggered by eruptions; the size of the latter waves may be indicative of the large size of eruptions. The submarine slopes are dissected by canyons and channels. The total volume of the volcano is about 269 cubic kilometres (65 cu mi), of which less than five per cent are above sea level.
Macauley Island
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