A reconstruction of late Quaternary erosional events in the West Tamaki River catchment, southern Ruahine Range, North Island, New Zealand

Abstract

Evidence is presented for the sequential nature of erosional events within a selected catchment of the southern Ruahine Range during late Quaternary time. The mapping of depositional surfaces, together with description of soil profiles and vegetation maturity on these surfaces, has enabled a chronology of erosional events to be established within the main channel of the West Tamaki River catchment. This chronology is aided by ages determined by: (1) radiocarbon dating of wood, and (2) a tephra, the Aokautere Ash, which has been identified on the main channel valley-side. An examination of the Takapari peaty loam, a Histosol which occurs at the head of the selected catchment, and the recognition of Taupo Pumice and Waimihia Formation tephras within it enable an interpretation of the erosional history of this soil site to be made.