Is a glacier gone when it looks gone? Subsurface characteristics of high-Arctic ice-cored slopes as evidence of the latest maximum glacier extent

Abstract

In the context of glacier retreat and increased precipitations, Arctic glacier basin slopes are subject to stress leading to visible transformations. In this work, subsurface features of a small Arctic glacier basin slopes are mapped using ground-penetrating RADAR. In combination with surface topography data, eight transects were surveyed ranging from the areas furthest from the current glacier extent to the areas still in contact with the glacier. This allowed for a reconstitution of the successive stages ice-cored slopes go through when glaciers retreat. It appears that slopes evolve from thick debris-covered ice bodies connected with the glacier, to residual ice and ice/debris mixes covered in debris. At the same time, surface morphology of the slopes shifts from homogeneous ice-cored slope gradients to more complex talus-type slopes at the end of the process. The stages of these evolutions are in compliance with former glacier extents. The main driving factors of the slopes successive stages are the constant slope adjustments linked to debris movements, and the melting of ice cores. All these factors are exacerbated by the warmer and wetter conditions they are subject to.