Holocene glacial activity in Mt Cook National Park New Zealand: The use of multi-parameter dating techniques to define glacial moraine chronologies

• Main Author: Gellatly, Anne F.
• Language: en
• Published: University of Canterbury. Botany 2010
• Online Access: http://hdl.handle.net/10092/4839

Holocene glacial moraines in Mt Cook National Park are re-dated by multi-parameter dating techniques. The deposits from six main valley glaciers were examined. In earlier studies by other workers the glacial moraine chronology of three of these valleys had been specified using radiocarbon, historical and lichen dating. Results from the present study are compared with this earlier work. A chronology of glacial events is here defined using historical, radiocarbon and rock weathering rind thickness dating. In addition, post-depositional surface modifications are described using changes in plant development, lichen growth and soil properties. The more precise dating methods delineate up to fifteen separate glacial expansion phases during the last 10 000 years. The weathering rind chronology defines glacial events around 7200,4200,3790,3350,2940,2540,2160,1830,1490, 1150,840,580,340,135 and <100 years ago. The chronology is strongly correlated with the radiocarbon dated glacial sequence; 8000, c.7000, 4200-4000, 3400, 2800, 2500, 2200- 2100, 1800-1600, 1100-1000, 800-700, 340 and 250 yr B.P. In recent historical times the glacial record is characterised by a number of local,minor advances prior to 1900, followed by a general still-stand until about 1930-40. During the last forty years all of the glaciers have been retreating. The widespread glacier recession supports evidence of a climatic warming in New Zealand since about 1930 which has intensified in the last thirty years. The Mt Cook glacial moraine chronology shows good agreement with the Holocene glacial record described from elsewhere in the Southern Alps of the South Island, New Zealand. A brief comparison with events associated with cool climate periods from elsewhere in the Southern Hemisphere demonstrates a similarity with events in South America, New Guinea, Australia and Antarctica. The present study indicates the need for revision of the original Mt Cook glacial moraine chronology which had implied extensive glacial expansion around the 17th century and which had grouped all of the events listed above as having formed in the last 1000 years.