The relationship between climate and rock glacier distribution in the Ben Ohau Range, New Zealand

Landforms of ice and debris transport marginal to the glacierized zone of the Southern Alps, New Zealand, have been classified into debris-covered glaciers, cirque floor lobes, and talus-derived rock glaciers. Mapping of fossil and active landforms reveals a zonation within the Ben Ohau Range in terms of both landform type and activity status. The dominant distinction of active forms is between relatively ice-rich forms (glacial origins) in the humid north and relatively debris-rich forms (periglacial origins) in the more arid south. A secondary altitudinal zonation distinguishes currently or recently active forms at high elevations from fossil forms at lower elevations. Estimates of mean annual precipitation and of the altitude of the -2 degrees C mean annual isotherm indicate that glaciers and active talus rock glaciers are located within the climatic boundaries identified for the European Alps. However, many fossil forms also occur within these boundaries where cirques are broader and shallower. These findings confirm earlier suggestions that permafrost occurs in the Southern Alps, but is restricted to a narrow zone above 2000 m. The study demonstrates the importance of relative ice-to-debris fluxes in determining the developmental pathways of landform genesis over both space and rime.