Geological Outline

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Geological Outline

The Three Kings area is a volcanic eruptive centre comprised of a cluster of scoria mounds and some basalt flow rock, contained within an approximately 1km diameter explosion crater. Basalt also flowed out of this crater to the north and down the valley through Western Springs to terminate as the Meola Reef in today’s Waitemata Harbour.

The violent eruption, which formed the crater, deposited ejected material known as “tuff” in a broadly circular fashion, creating a “tuff ring”. This was superimposed on the then existing landscape, which has been inferred as an undulating ridge, continuous with that along today’s Hillsborough Road. This had been formed by erosion of the local “Waitemata” Group basement rock – sandstones and mudstones – by a pre-eruption drainage system.

Within the tuff ring over some period of time basalt lava or magma from the earth’s core breached the surface in several places in several ways. As noted before some lava welled up within the ring and in places overflowed the lip. There was also “fire fountaining” of lava material as it actively de-gassed and this formed several scoria cones within the crater/tuff ring complex.

The name “Three Kings” has derived from the fact that there were three large cones dominating the original cone complex. Today only one large cone, known as “Big King” remains on the Auckland Council’s Big King Reserve.