Column of basalt lava from a lava flow - the rongo stone of pre-European Maori gardens.
Maungakiekie is the second largest volcano in the Auckland Volcanic Field. It is a "fried egg" volcano composed of a central (yolk) scoria cone surrounded by a large lava flow field (white of egg). The early lava flows were hot and fluid and spread out over a large area of the Auckland Isthmus as far as Newmarket, Ellerslie Racecourse and the Onehunga foreshore. The lava flows of One Tree Hill Volcano underlie all or part of the following suburbs: Newmarket, Epsom, One Tree Hill, Royal Oak, Onehunga, Greenland, Oranga, Penrose, Ellerslie and Remuera. The later (youngest) flows were cool and viscous and exuded out from part way up the scoria cone slopes and flowed no more than 100 m from the cone with steep lava flow fronts. The central scoria cone complex has three craters from which fire-fountaining eruptions occurred to produce the scoria cones.
Two of the craters have only three sides and have been breached by lava flows which flowed outwards and rafted away some of the scoria ramparts.
There are spectacular views of the Auckland Volcanic Field from the summit.