Auckland’s landscape is dotted with the cones of volcanoes that erupted comparatively recently in geological time, with the oldest (Auckland Domain) erupting 140,000–150,000 years ago. There are 48 volcanoes in the Auckland volcanic field, all within about 20 km of the city centre.
Auckland’s volcanic cones were important sites of Māori occupation. They were ideal for palisaded fortresses, and were usually ringed with terraces of housing, storage pits, and large gardens on the fertile surrounding soil. European settlers in turn favoured the warm northern slopes for housing, and quarried volcanic basalt and scoria for buildings, walls, railway lines and roads. While the wide lava fields are built over today, the higher slopes of most of the cones are reserved as parks.
Volcanoes interrupt a battle
In a traditional Māori account, Auckland’s volcanoes surfaced during a battle between the peoples of the Waitākere and Hūnua ranges. The Hūnua tohunga (priest) invoked the sun to rise early and blind the Waitākere warriors, and as a result many were killed. But when the Hūnua people advanced against remaining Waitākere forces, a shield of volcanic explosions across the isthmus stopped them in their tracks. Auckland’s scattered volcanoes stand as a remnant of the battle scene.
Auckland’s most visible volcanic cones
The largest, youngest and most recent is Rangitoto Island, which erupted only 600 years ago, ejecting as much lava as all the other Auckland volcanoes combined. The symmetrical cone and wide-spreading lava flow make it one of Auckland’s major icons. Nearby Browns Island (Motukorea) is the only Auckland volcano not to be quarried, and has a clearly visible symmetrical cone and crater, and a partial tuff ring. Maungawhau (Mt Eden) is the highest on the Auckland isthmus (196 m), with three overlapping cones, one with a deep conical crater. The terracing and pits of Waiohua’s settlement remain, and its summit is a tourist look-out point.
Maungakiekie (One Tree Hill) is the largest after Rangitoto, 183 m high, with three craters. Its lava flow covered 46 sq m and reached Manukau Harbour. As the home of Kiwi Tāmaki, paramount chief of the Waiohua in the 18th century, it was probably the largest earth fort in the world, and was famed for kūmara gardens covering 1,000 hectares. Māngere mountain (107 m), the last of the Waiohua strongholds, dominates the landscape of South Auckland.
No Tree Hill
Maungakiekie was given its European name (One Tree Hill) by Sir John Logan Campbell, after a tōtara tree (Te Tōtara i Āhua) that stood on its summit. This was felled by a Pākehā settler in the 1850s. Campbell tried to replace the tōtara with a grove of trees, but only a single monterey pine tree survived. This became an Auckland landmark. After attacks by Māori protesters in 1994 and 2000 the tree was felled in 2001 for safety reasons.
Lakes in craters
Some of the craters filled with water, forming lakes and basins. Lake Pupuke (100-150,000 years ago) was probably formed by lava flowing back into a collapsed crater, which filled with fresh water. Ōrākei Basin and Panmure Basin were infiltrated with sea water.
Most of Auckland’s volcanic cones were modified by Māori and more extensively by Pākehā settlement. At least half have been made almost unrecognisable by quarrying: Mt Smart’s 50-m cone was completely excavated and large portions of Mt Albert (Ōwairaka) and Wiri mountains were taken for railway-line ballast. Several South Auckland cones disappeared in the course of the construction of Māngere airport and sewerage ponds.
The Franklin field
Further south, in the Franklin area, are much older volcanoes (500,000–1.5 million years). From Papakura to Pukekawa there are 80 ancient volcanoes, less striking than those nearer to Auckland because they have been weathered with age. The most extensive market gardens in the region are on this fertile volcanic soil, especially around Pukekohe and Bombay.