The Hinteres Langtalkar rock glacier (Gössnitztal, Hohe Tauern, Austria) has been part of a complex transportation system of debris and ice since the beginning of the Holocene and shows the highest creep rates of all rock glaciers measured in the Hohe Tauern Range. Results of movement analysis show that the entire rock glacier behaves very differently at different zones and that sudden temporal and spatial changes of velocity rates are a typical feature. Zones with high rates occur close to rather inactive zones and zones with low rates have rapidly accelerated within recent years. The increase in movement rates over time is probably caused by topography. These studies – especially the measurement of surface velocities and elevational changes – allow a differentiation of the rock glacier and a first attempt of a morphogenetic interpretation. In this context, it is important that the innermost part of the cirque was covered by a small cirque glacier during the Little Ice Age advance. This cirque glacier created a moraine complex which contributes to the material supply of the rock glacier. A first estimation of transportation rates is possible with the help of the measurement results available, leading to an estimation of a probable age of at least 4000 years.
Acknowledgements
Aerial photograph for 1969, 1991, 1997, and 1999 © Austrian Federal Office of Metrology and Survey (BEV), Vienna, 2001. All photographs were scanned using the UltraScan 5000 of Vexcel Imaging Austria – the kind support of M. Gruber is greatly appreciated. R. Ladstädter (Institute of Remote Sensing and Photogrammetry, Technische Universität Graz (TUG)) has developed the ADVM software used in this study. His contribution to the present work is greatly acknowledged. We would also like to thank G. Kienast (Institute of Navigation and Satellite Geodesy, TUG) for his professional support during the geodetic surveys, and also A. Kellerer-Pirklbauer and H. Wakonigg (Institute of Geography and Regional Sciences, Uni Graz) for providing photographs, reviewing the manuscript and making helpful suggestions.