Current transition from glacial to periglacial processes in the Dolomites (South-Eastern Alps)

- We investigated the geomorphology and the evolution of an alpine composite landform.
- Geomorphological surveys were combined with various techniques and methods.
- The lower part of the landform is an active rock glacier containing a frozen body.
- The upper part is a Little Ice Age glacial remnant now inactive and debris-covered.
- A change from glacial to periglacial processes occurred in this area since the LIA.

A close relationship between glacial and periglacial landforms is frequently observed in alpine environments, where a transition from glacial to periglacial processes often took place after the end of the Little Ice Age (LIA). Understanding the origin of these landforms is challenging, and assessing the current spatial domain of glacial and periglacial processes may be a difficult task in high-relief areas, where thick and widespread debris cover often characterize rapidly decaying glaciers. Here we present a comprehensive study of a composite landform located in the Dolomites (South-Eastern Alps), combining geomorphological, geophysical and topographic surveys with ground surface temperature measurements. Results indicate that a debris-covered glacier persists in the upper part, rather large compared to the LIA extent, but currently inactive and rapidly losing mass. An active rock glacier exists in the lower part, surrounded by discontinuous permafrost. A frozen body about 10 m thick was detected in the rock glacier and geomorphological evidence suggests that this ice mass is completely detached from the debris-covered glacier. Our findings suggest that the lower part of the composite landform is probably a remnant of the ancient glacier tongue and is currently evolving under periglacial conditions. Periglacial processes are therefore replacing glacial processes which dominated in this site during the LIA.