During Quaternary time, the history of the Te Werahi area included episodes of dunefield formation alternating with periods of extensive erosion of sand cover. Dune units of last interglacial age and older crop out as isolated erosional remnants within and adjacent to an extensive Holocene dunefield. The latter had begun to form by at least 4000 years BP, and dune mobilisation continued until about 1800 years BP, possibly with increased dune movement after 3000 years BP. A smaller Holocene dunefield on Motuopao Island also formed before about 1800 years BP. After 1800 years BP, the Te Werahi and Motuopao dunefields entered a stable phase that persisted until about 450 years BP, followed by dune remobilisation and erosion that has continued to the present day. Analysis of fossil landsnail faunas indicates that forest was widespread in the Te Werahi area in mid Holocene time, was mostly over-run by dunes by about 1900 years BP, and then locally re-established on the dunefield between about 1800 and 800 years BP. That dune forest was destroyed between 800 and 550 years BP, probably as a result of anthropic firing following Polynesian settlement, and has not subsequently re-established. Vegetation disturbance on the Te Werahi dunefield since at least 4000 years BP has resulted in cumulative extinctions and impoverishment of native landsnail faunas, especially during major extinction pulses before 1900 years BP and between 800 and 550 years BP.
