07/05/2024
What is the oldest volcano in Auckland? This answer may not be what you think. Auckland has many volcanoes and not all of them are in the Auckland and South Auckland volcanic fields. Indeed, there are some ancient volcanoes all around the supercity.
The oldest are part of the Northland-Mohakatino Volcanic Belt, which runs from Whangārei Heads to Taranaki. The Waitākere Ranges were once the eastern edge of a massive stratovolcano that erupted between 22 and 15 million years ago. The crater has largely eroded into the Tasman Sea, but the east side was lifted by plate tectonics. Te Piha—Lion Rock at Piha Beach—was once a volcanic plug that issued out of a vent 17 million years ago.
While the Waitākere Volcano was still erupting, new vents opened in the Kaipara and along the Coromandel. Spanning both sides of the Oruawharo River near Tāpora, a small lava vent erupted about 18.5 million years ago. The lava quickly cooled creating volcanic glass. Meanwhile, a series of volcanoes appeared between 18 and 8 million years along the eastern edge of the Hauraki Gulf helping create the Coromandel Peninsula and Aotea Great Barrier Island.
While the Coromandel Volcanic Zone was still active, basalt plugs began appearing along today’s east coast. Tī Point, Goat Island, and four other plugs popped up around Leigh, while a related set created Waiheke Island’s Stony Batter. About 3 to 1 million years ago, the zone spawned one last surprise, Hauturu Little Barrier Island, the last significant volcano to erupt outside the two better-known fields.
Image: Albert Hague Jones. Lion Rock, Piha, ca 1910. Auckland Libraries Heritage Collections 7013-030. bit.ly/pihalion