What Happens: Glaciers are in constant motion,
so parts of the ice pack can become unstable because of factors like natural movement
and changes in temperature. Glaciers on steep slopes, in particular, tend to break
off rather than melt away, causing ice avalanches. In April four skiers in the
Mont Blanc range perished when a serac an ice pinnacle formed where the glacier's
surface is torn by cracks-broke away and crushed them. The most catastrophic scenario
is when the front of...