I was reading through an excellent archived National Geographic
articles on the geological activity, history and threats posed by the Cascade
volcanic peaks [1998].
What struck me in the magazine article was the surprising information
that hard, solid rock within volcanic peaks can literally "rot" [that was the word used] from the effects of highly corrosive [acidic?] geothermally-heated water worming its way through
the strata within the volcanic peaks; even turning hard rock into sand and clay.
One of the lessons learned from the eruption of Mount St. Helens, 25 years ago.

Interesting!
But what does this have to do with Mars?

Well...There are some impressive [extinct or dormant] volcanic peaks on Mars for one thing..

And?...We know that Mars has had, and may still have, abundant geothermally-heated
subsurface water that would also be highly corrosive....

The results from the Spirit rover virtually confirm that that part of Mars [the hills within Gusev Crater] at one time long ago had geothermally-heated subsurface
water seeping through the rocky strata making up the hills...and that the geothermal water
was highly corrosive [acidic].

Which leads me to this question: Are the hills within Gusev Crater liable to collapse from
the effects of the corrosive subsurface geothermal waters that seeped through them at one time?...Or has the time for such
slumpage and collapse come and gone a long time ago?

cheers.

Jake