An early Holocene glacial advance in the Macaulay River valley, central Southern Alps, New Zealand

Abstract

Abstract A 10 km long valley glacier terminating between Lower Tindill and Tom Streams, in the Macaulay River valley, central Southern Alps, New Zealand, at 8690 ± 120 years B.P. (NZ 6473A), is inferred from radiocarbon-dated deposits of till that were formerly thought to be of nonglacial origin. The glacial advance is one of three dated early Aranuian (post-14 000 years B.P.) advances in South Island. A group of undated moraines to the east of the Main Divide of the Southern Alps, collectively known as the Birch Hill moraines, may include moraines of similar age to the Macaulay River deposits,butrepresenta substantial interval of time. Available radiocarbon dates suggest that previous correlation of Birch Hill moraines with the c. 12 000 year old Waiho Loop moraine at Franz Josef Glacier is unlikely. Early Holocene glacial deposits of similar age to the Macaulay deposits are found in arctic Canada, western United States, and in the European Alps, so the triggering minor climatic change may have been global in extent. If the event formed moraines elsewhere, they remain undated, and may lie beneath present-day ice or have been destroyed by subsequent neoglacial advances.