Glaciers as witnesses ...
Glaciers arise where the temperatures in summer are not sufficiently high to melt the snow which falls in winter. In this way, snow layers accumulate year by year and, after being changed into corn snow, solidify due to the increasing pressure to form ice. Thus, glacial ice is not a rigidly solid body and flows into the valley as a viscous mass, following the pull of gravity.
The overflowing of knolls in the terrain gives rise to wrenching forces which tear open crevasses. Although the glaciers of the Alps have been retreating for decades, the Hohe Tauern region still retains impressive treasures from the ice mountains today: such as the Pasterze Glacier - which, with a length of 9 km and an area of almost 19 km2, is the biggest single glacier in Austria. Or the Grossvenediger Mountain, which is crusted with the ice of the largest connected glacial area in the Eastern Alps.
Where glaciers have retreated, a fast changing landscape comes into being: at first, the landscape is still dominated by the debris moraines piled up by the glacial ice, but soon the pioneers of the plant world begin to recolonize this seemingly inhospitable habitat.