Lichenometry as a relative-age dating method in Mount Cook National Park, New Zealand

Abstract

A study of the Holocene glacial sequence at Mount Cook National Park, New Zealand lead to revision of proposed chronology and re-examination of lichenometric dates for the area. Glacial deposits were up to one order of magnitude older than was previously thought and the original lichen record has been re-calibrated using the new dates. Additional measurements of lichens were collected from the eastern end of the Park and compared with ages of the moraines. A revised lichen growth curve was produced for glacial deposits formed during the last 1000 years. The rate of lichen growth declined on some older surfaces with increased competition from vascular plants. Calibration of the lichen growth curve was only possible where independent dates were available. Rates of rock weathering rind development, soil development, and plant succession were all useful for the re-calibration. Many radio-carbon dates greatly aided the construction of the chronology.