Question - How can the thinning and recession of a glacier contribute to the probability of slope failure?

How can the thinning and recession of a glacier contribute to the probability of slope failure?

Answer: 

For the past tens of thousands of years alpine glaciers have pressed up against valley walls, compressing the rock and allowing it to maintain steep slopes. With the thinning and recession of glaciers that support is being lost and rock faces are also expanding and losing strength, increasing the probability of slope failure.