Stratigraphic and plant microfossil investigation at Cook's Cove, North Island, New Zealand: reinterpretation of Holocene deposits and evidence of Polynesian-introduced crops

Abstract

A shoreline and archaeological excavations at Cook's Cove, eastern North Island, New Zealand were examined for stratigraphy and plant microfossils and results compared with previous interpretations of this site. Buried soils, distal tephras and pollen revealed evidence of pre- and post-settlement forest disturbance. Microfossil starch and calcium oxalate crystals of introduced sweet potato (Ipomoea batatas) and taro (Colocasia esculenta) were identified throughout the deposits, indicating intensive local cultivation and processing of these crops. Results are consistent with revised New Zealand geochronological models and, bearing in mind loss of evidence by erosion, differ in several respects to those of previous studies, as follows. The sea-rafted Taupo Pumice (AD 200) and Loisel's Pumice (from multiple off-shore sources) were not as widespread. Although microscopic charcoal was present to the full depth of all profiles, we did not observe macroscopic pieces below the Loisel's Pumice. The only material we found that appeared to equate to the deposit previously identified tentatively as air-fall Kaharoa Tephra (AD 1300) appeared not to be a tephra. Finally, we found little evidence for marine inundation of the site.