Rangitoto Island field trip, Auckland

Abstract

Rangitoto, Māori for ‘blood red sky’ (also ‘lava, scoria’), derives from the phrase Ngā Rangi-i-totongia-a Tama-te-kapua (the full name for the island) meaning “the day the blood of Tamatekapua was shed”, referring to a battle between Tamatekapua and Hoturoa, commanders of the Arawa and Tainui canoes, respectively, at Islington Bay. The Island is arguably Auckland’s most beloved and omnipresent landscape feature. It is a symmetrical, ~6-km wide, basaltic shield volcano that last erupted c. 550‒500 calendar/calibrated (cal.) yr BP (c. 1400‒1450 AD), not long after arrival and settlement of Polynesians in the Auckland region (c. 1280 AD). It is by far the largest, and the youngest, volcano in the Auckland Volcanic Field (AVF). The AVF consists of ~53 individual eruptive centres, all of which lie within the boundaries of the Auckland urban area. Recent research on deposits in a 150-m-long drill core obtained from Rangitoto Island in February, 2014, and on cryptotephras in sediments from Lake Pupuke on North Shore and on tephras in wetlands on adjacent Motutapu Island, has revealed Rangitoto’s complex history, with three main phases (1‒3) suggested. The flora on Rangitoto is unique among the islands situated in the Hauraki Gulf because of the island’s young age, and the fact that technically Rangitoto is an ‘oceanic’ island. Its flora and fauna are derived entirely from long distance dispersal. The island contains some 582 vascular plant taxa of which 228 (39%) are indigenous.