The role of Egmont-sourced tephra in evaluating the paleoclimatic correspondence between the bio- and soil-stratigraphic records of central Taranaki, New Zealand

Abstract

On the lower eastern flanks of Egmont Volcano, western North Island, New Zealand, several Egmont-sourced tephras have been correlated to a radiocarbon dated peat site that provides a late last-glacial to early post-glacial record of vegetation and climate change in central Taranaki. The pollen spectra at this site indicates a mosaic of grassland-shrubland and Prumnopitys taxifolia-dominant forest at ca. 13,100 BP and suggests a climate cooler and drier than at present. The ominance of tall podocarp forest by ca. 12,900 BP suggests that climatic amelioration was rapid towards the end of the last glacial period. Initially this forest was dominated by Prumnopitys taxifolia but at ca. 11,000 BP was succeeded by Dacrydium cupressinum indicating a steady shift to warmer and moister climate. Tephra interbedded with peat allows precise chrono-correlation into the Andisol-forming environment. The rapidity of climatic amelioration identified from variations in Andisol morphology and mineralogy concurs with that indicated from pollen changes in the peat.