Pollen analysis of late Otiran and Aranuian sediments at Blue Spur Road (S51), North Westland

Abstract

Abstract In a section exposed along the Blue Spur Road, Terangi Interglacial marine gravel is overlain by Waimea Glacial outwash gravel beneath the outwash aggradational surface. Colluvial gravel and silt in a channel on that surface are interpreted as representing the early stadial in the Otira Glacial, and, judged by radiocarbon dates and pollen analysis, peat and loess represent an interstadial, the later Otiran stadials and the post-glacial (Aranuian). Only the later part of the interstadial is recorded in the pollen-analysed section. Dacrydium cupressinum forest is replaced by forest of the Nothofagus fusca type which in turn was followed by N. menziesii forest. The N. menziesii was accompanied by an increase of grassland and dicotyledonous shrubland and was succeeded by Dacrydium cupressinum forest in the post-glacial. The interstadial is inferred to have begun some thousands of years before 30,300 B.P. and to have lasted until about 25,000 B.P.