LITTLE ICE AGE CHRONOLOGY FOR THE CLASSEN AND GODLEY GLACIERS, MOUNT COOK NATIONAL PARK, NEW ZEALAND

A Little Ice Age (LIA) glacial chronology for Classen and Godley Glaciers provides a record of climate change and can help determine if Holocene climate change occurred synchronously between the two polar hemispheres. Ages of ice margin positions were determined from lichenometry, historical records, and radiocarbon dates. Ages indicate initiation of advance no later than ~1790 AD. Maximum extent occurred by ~1862 AD. Retreat patterns suggest three phases of retreat. Phase one, the slowest phase, lasted from the 1860's to the 1890's for both glaciers. Total marginal retreat for both glaciers was ~100 m. Phase two, with a slightly higher retreat rate, lasted until the 1950's, during which the Godley separated from two of its tributaries, the Grey and Maud. Total marginal retreat by the end of the second phase was ~1 km for the Classen, ~3 km for the Grey and Maud, and ~5 km for the Godley. Phase three, with the highest retreat rate, began with the formation of a pro-glacial lake at each of the three ice margins, included the separation of the Grey and Maud in 1990, and continues today. Total marginal retreat has been ~3.5 km for the Classen, ~4 km for the Grey and Maud, and ~7.5 for the Godley.

Northern Alaskan and Scandinavian LIA maximums correspond to the initiation of the recent New Zealand LIA advance. The New Zealand maximum ice extent in 1862 matches LIA maximums from Iceland, Switzerland, Southern Alaska, and British Columbia. During the retreat phase no evidence of minor readvance is observed in New Zealand, but is observed in many Northern Hemisphere retreat patterns during the 1930's. A more complete account of the retreat pattern in New Zealand could be achieved by considering the change in ice volume in addition to change in ice margin position.