QUESTION:
I've heard about the erosion of the surface due to liquid water.  Is there
any evidence of glacial movement and erosion associated with glacial
movement?

ANSWER from Bruce Jakosky on July 18, 1997:
The question of glacial movement and erosion is a difficult one. Certainly,
water ice is stable very near the surface over much of the planet, and even
where it is not stable it can survive for long periods of time.  There is
some clear geological evidence for ice in the martian surface materials. For
example, there are debris flows around some mountains and in some valleys
that appear identical to glaciers and rock glaciers on Earth.  (Rock
glaciers are mixtures of rock and ice that flow as if they were primarily
ice.) The north polar cap is primarily water ice, and there have been some
suggestions that it has flowed like a glacier.

Most intriguingly, there are some features that have been interpreted as
resulting from widespread glaciation.  These include features that look like
terrestrial cirques, kettles, and melt runoff.  These are speculative,
however, and may result from other causes.

I think that it's clear that ice has been a major player in the history of
the martian surface, but the specific role that it has played is not well
defined.