The Influence of Topography on Snowpatch Distribution in Southern Iceland: A New Hypothesis for Glacier Formation?

ABSTRACT

A fundamental distinction exists between the initial glaciation of an upland landsurface, and all subsequent re-glaciations of the same uplands. Unfortunately, few areas of the world present an opportunity for the study of initial glaciation, since most glacial or periglacial regions have already undergone multiple glaciations throughout the Quaternary. Concepts of how glaciers are initiated and enlarge are inevitably influenced by the fact that models can only be derived from, and applied to, landscapes whose topography already demonstrates modification by glacier ice.

Observations of snowpatch distribution in Southern Iceland allow us to examine this distinction between initial glaciation and re-glaciation. High resolution remotely sensed data were obtained showing the distribution of snowpatches at two topographically different sites, one previously glaciated and the other a young volcanic landscape that has remained unglaciated since the central caldera erupted, forming the basis of the present topography (Saemundson 1979). Both locations are only marginally unglaciated at present. Comparison of these distributions suggests that whilst the conventional “top-down” model of glacier growth may be appropriate for reglaciated uplands, a “bottom-up” model may be more applicable to steeply dissected upland terrain experiencing initial glacierisation. The importance of this distinction between initial glaciation and reglaciation in terms of erosion and deposition is also considered.