Franz Josef Glacier Valley
Alexandra Garfinkel and Trevor Bloom
The Franz Josef glacier is located immediately west of the main divide of the Southern Alps in New Zealand, a rapidly uplifting 400 km tectonic plate boundary between the Pacific and Australian plates. It is likely that the Franz Joseph Glacier arrose in last 2 million year with the uplift of the southern alps, however, it can only be scientifically traced back 12,000 years with rocks found in the terminal morrain known as the Waiho Loop.
A glacier acts as a giant conveyer belt which carries away rocks that fall from the valley and excavates bedrock over thousands of years. This creates a distinctive u-shaped valley (2). The rate at which a glacier moves depends on three key factors, precipitation over the glacier, the slope of the valley, and the width of the neck in relation to the neve, i.e. the main basin of the glacier (2). Franz Josef is one of the fastest glaciers in New Zealand, moving an average of four meters per day (2). This incredible turnover was first noticed after a plane that wrecked in 1949 was carried four kilometers over six years and fell off the terminal face of the glacier (2).
There have been four major cycles of advance and retreat glacier movements on the South Island over the past 250,000 years. About 14,000 years ago, glaciers that had formed during these ice ages retreated as temperatures rose rapidly, leaving them tiny in comparison to their ancestors (2). Currently, the extent of glacier ice in New Zealand is less than at any other time in the past 5000 years (1). In the past century, there has been an overall mean retreat of 1.3km of New Zealand glaciers, possibly linked to a .6 °C increase in temperature (1). Between 1980 and 1999 a slight but steady advance in the Franz Josef glacier was recorded, probably due to high snowfall in the neve(3, 4), however, since 1999, the glacier has again been receeding.
1. Hutching, Gerard. The Penguin Natural World of New Zealand. Auckland: Penguin Press, 1998. Print.
2. Coates, Glen. The Rise and Fall of the Southern Alps. Christchurch: Canterbury University Press, 2002. Print.
3. Orleans, J. (1997). Climate sensitivity of Franz Josef Glacier, New Zealand, as revealed by numerical modeling. Arctic and Alpine Research, 29(2), 233-239.
4. Goodsell, B., Anderson, B., Lawson, W. J., & Owens, I. F. (2005). Outburst flooding at Franz Josef Glacier, South Westland, New Zealand. New Zealand Journal of Geology and Geophysics, 48(1), 95-104. Retrieved from www.tandfonline.com/doi/abs/10.1080/00288306.2005.9515101