Glacier trekking demands a profound knowledge of the environment, correct equipment and a good sounding in the techniques required. The glacier is in constant transformation and the dangers vary according to the seasons and to temperatures, as well as to its thickness and orientation.
The glacier is at its most dangerous where there is snow, and more particularly,
in summer. It is better to move about on the ice than on snow that may be
hiding crevasses.
On the flat part of a glacier, snow that has given way, or a change in colour
and or luminosity are usually signs of a crevasse. Crossing a bergschrund
is difficult in certain cases such as where the snow is of poor quality,
if the bergschrund is pretty much open or if there is a sharp wall of ice.
Here, an excellent knowledge of the techniques of assurage is essential. If you have to cross
a crevasse, you must correctly judge the width (and not depth) of the obstacle,
to check oneself and to belay one another. When crossing a glacier
you must be in a roped party at all times and must respect a distance of
10 to 15 m between each mountaineer.