Introduction

Talus deposits are widespread in arctic and alpine environments, and represent an important sediment store in these regions. However, detailed information on total thickness and structure of the sediment bodies is sparse. Ground-penetrating radar offers a promising approach to collect data on loose debris quickly and in high resolution. The damping of radar waves is primarily dependent upon the dielectric constant and on the electrical conductivity of the subsurface. Talus deposits are usually very dry and thus very high-resistive (similar to scree slopes, see Chapter 10). Accordingly, the basic preconditions for GPR measurements are very good.

Study sites and data acquisition

The exemplary radargrams presented were measured in the Lechtaler Alps and in the Kühtai area (Austria) from 2003 to 2006 (Figure 11.1). The ‘Parzinn’ is a wide cirque in the Lechtaler Alps at an elevation of 2000–2700 m. Large talus cones have developed under dolostone rockwalls. Most of the cones end downslope at the reverse angle of late-glacial moraine ridges. In numerous radar profiles, a penetration depth of up to 50 m was achieved. The results were validated by additional geoelectric and seismic measurements (Sass2006). The Kühtai area lies in the Central Alps at an elevation of 2300–3000 m, the rockwalls consist of gneiss and mica-schist. Two steep talus cones were investigated by GPR and geoelectric longitudinal and cross profiles. One of the cones ended downslope at a small lake.

For the investigations presented, a RAMAC GPR (MALÅ Geosystems, Sweden) was used.