Postglacial talus slope development imaged by the ERT method: comparison of slopes from SW Spitsbergen, Norway and Tatra Mountains, Poland

Abstract

Talus slopes are a common sedimentary formation both in polar and high-mountain areas, but their development is still not sufficiently understood. This article discusses the environmental factors that have been influencing development of talus slopes since the deglaciation and their impact on the internal structure of slopes. Case studies of the slopes from SW Spitsbergen and the Tatra Mountains in Poland were compared in order to explore different evolution stages. Slopes’ structure was analysed using geophysical surveys based on two-dimensional electrical resistivity tomography (ERT) with a Wenner-Schlumberger array and an electrode spacing of 5 m, combined with geomorphological observations. The investigated talus slopes represent the paraglacial, periglacial and talus-alluvial environments. New data on the internal structure of talus slopes developing in the present or past glaciated areas adds to understanding talus slope evolution. There are many different views concerning the development of slopes during the paraglacial period, whose analysis seems to be crucial in the background of climate change and their record in slope structures. In addition, the study provided valuable information on the development and degradation of permafrost in slope materials.

Processes controlling the development of talus slopes in SW Spitsbergen: The role of deglaciation and periglacial conditions

“…Talus cones develop at their foot. In many shady places there are snow and firn patches that melt in summer and provide water to the upper parts of the talus slopes (Senderak et al, 2019). Opposite Skoddefjellet the rock slopes are less fragmented and less inclined and on their upper parts there are debris-mantled slopes.…”

“…In addition to the intense activity of the glacial processes accompanying glacier recession, geomorphic processes are simultaneously in operation throughout the entire periglacial zone. Therefore talus slope development depends on environmental factors, such as the geology of the area (especially lithology) and the size of the sediment supply area (Senderak et al, 2019).…”

“…The movement of BGI to the flat bottom of the valley was not dependent on the direction of the glacial ice masses in the valley, but it could be a reason to form subslope rock glaciers with a depression between the talus slopes and the subslope ridges (Figure 12C). This stage, called a paraglacial period by Senderak et al (2019), is characterised by the predominance of paraglacial processes and the eventual development of a proglacial lake (later a postglacial lake). In this end-stage phase of deglaciation, the ice core of the talus slope is subject to degradation and also deformation, the result of which can be, as Ballantyne ( 2002) suggests, an undisturbed development of subslope rock glaciers in periglacial conditions.…”

“…Marginal parts of glaciers are covered by talus deposits through which they can become part of the internal structure of talus slopes. Buried glacial ice survives deglaciation preserved in the slope material, and plays a significant role in the paraglacial period of talus slope development (Senderak, Kondracka, & Gądek, 2019).…”

“…At the same time, researchers have begun to analyse the development of talus slopes more and more confidently, being convinced that information about the course of glaciation is recorded in an increasingly accessible internal structure, for example, Gądek, Grabiec, Kędzia, and Rączkowska (2016) on the influence of climate change on the structure and morphodynamics of talus slopes, Onaca, Ardelean, Urdea, Ardelean, and S ar aşan (2016) on the genetic typologies of talus slopes or Tomczyk and Ewertowski (2017) on morphological types of fan-shaped landforms. The dynamics of change in the glacial environment have a significant impact on the development of the internal structure of talus slopes, which is why these forms can be a valuable source of data on the course of deglaciation (Senderak et al, 2019).…”