One Tree Hill

Maungakiekie

In terms of the area covered, One Tree Hill is one of the largest volcanoes in the Auckland Volcanic Field. It is a prominent Auckland landmark.

The Auckland Volcanic Field is comprised of monogenetic volcanoes which means it is unlikely that One Tree Hill or any of the existing volcanoes will erupt again. The next eruption will probably occur in a new location.

Formation

One Tree Hill scoria cones erupted about 20 000 years ago. Three large volcanic craters were formed and lava flows created 20 square kilometres of lava fields. The majority of the lava flowed towards the Manukau Harbour and covered almost the entire Onehunga area. Lava flows filled up ancient valleys. They formed thick deposits and created paths for groundwater flows.

The summit peak of the scoria cone overhangs a small oval crater and appears to be the remains of a larger structure that was destroyed in later eruptions. Two large breached craters in the north and west were the sources of energetic lava flows and resulted in the spectacular amphitheatres of One Tree Hill.

Use and value

Archaeological surveys have identified over 170 constructed terraces focused around 3 Maori Pa (fortifications). Since the 1840s the hill has been reserved. In 1901 John Logan Campbell gifted the adjacent Cornwall Park to the city. The highest point of the hill is topped with a single pine tree (replacing the original native Totara), a monument, and the grave of Sir John Logan Campbell, the 'founding father' of Auckland City. One Tree Hill is a significant cultural landscape.

It is one of the largest Maori settlement complexes in Aotearoa - New Zealand and has been claimed to be the largest pre-historic earth fort in the world. The cone and its surrounds are protected both as an archaeological and a geological feature in the Auckland City Isthmus District Plan.

Some lava flows extend 2.4 km to the coast at Onehunga. These lava flows contain many caves. Groundwater soakage in these lava flows provides a plentiful water supply that is still in use today. Water supply wells in Onehunga are able to provide more than 20 000 cubic metres of good quality drinking water per day.

One Tree Hill was quarried up until 1957. Approximately 25 000 cubic metres of scoria has been removed by quarrying.

Today One Tree Hill is a popular recreational reserve. Its grassy slopes and gardens are popular with picnickers and joggers. The summit is popular look out from which you can get a good perspective of the Auckland Isthmus. One Tree Hill is also used for grazing stock.

Key facts

Maori name: Maungakiekie, 'hill of the kiekie vine'
Location: Auckland City, map reference NZMS 260: R11/692764
Height: 183m
Age: Formed 20,000-30,000 years ago
Volume lava: 325 million cubic metres (equivalent to 65,000 Olympic sized swimming pools)