while two others were horseshoe craters, lacking one side where the lava flowed away from the vent. The lava from One Tree Hill flowed down old stream valleys towards Onehunga. In the process it blocked the drainage for parts of the isthmus north of the hill allowing sediment to accumulate there forming the plain between One Tree Hill and Mt St John. Some of the lava flows formed tubular channels of cooled volcanic rock through which the hot lava flowed. Late in the eruption this drained away leaving lava tube caves which are often found in the Auckland volcanic field.
There is a volcanic trail on the mountain. Collect the trail guide at the Information Centre and watch the introductory film at the Maungakiekie Education Centre. Maungakiekie is the most extensively terraced of all the Auckland volcanoes. Over 170 of these terraces remain in Cornwall Park and One Tree Hill Domain. These earthworks cover approximately 45 hectares, making Maungakiekie one of the largest pa in New Zealand.
The traditional occupants of Maungakiekie were the Wai o Hua tribe. Their traditional history refers to the site as the head pa of their paramount chief, Kiwi Tamaki. The Wai o Hua people occupied the site in the early 1700's and most likely earlier than that. Other Auckland iwi, including Ngati Whatua o Orakei can also trace their ancestry to people who occupied the site.
Like the other volcanic cone pa it was not occupied at the time of European exploration and settlement, for reasons which are not fully understood. Certainly many people still lived in the area. Defeats in warfare, exhaustion of forest resources as the forests were cleared and the difficulty of defending such large sites may all have been factors.
The Rongo stone set in a plinth near the main barbecue area is an unusual remnant of a Maori shrine. Maori religious concepts seldom took physical form but Rongo is an exception with objects and carved stones being seen as manifestations of the god and used ritually to aid the growth and harvesting of crops.
This naturally shaped columnar stone was part of a shrine at Three Kings though it had, according to tradition, been moved there from the upper Waitemata. It was called Te Toka i Tawhio - "the stone which has travelled all around". Campbell rescued it from a roadside where it had been dumped and moved it to Cornwall Park.

The last tree on top of One Tree Hill was a pine tree - Pinus radiata - the most common tree grown for timber in New Zealand. Another Maori name for the hill is Te Totara i Ahua which refers to a sacred totara tree (Podocarpus totara) and can be translated as "the totara that stands alone".
The name One Tree Hill was applied to the hill by early European settlers because of the single tree growing there. The tree was the totara, sacred because of its association with the cutting of a baby's umbilical cord, an important ceremony in Maori society. The event commemorated by the planting, the birth of a boy called Koroki. That tree was cut down in 1852 by a party of workmen, reportedly angry at the non-arrival of some rations. Attempts over the years to re-establish a totara on the summit have all failed. In October 2000 Auckland City Council deemed the tree unsafe due to its dwindling health after a number of attacks in recent years. The icon was removed on the 26 October 2000. The Council are planning to replant a series of smaller trees over the next planting season (May - August).