On the east coast of the North Island the underlying geology consists of weakly cemented sandstone and mudstone. With rainfall, such slopes fail very easily even on gentle topography. Saturated with water, this earth flow had the consistency of wet cement. From where it originated (top left) it moved down a gully (centre) towards Mangataikapua Stream, which it has blocked. Landslides are the main force shaping this undulating terrain.
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Photograph by Lloyd Homer
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