Thanks for your response. You insight is helpful. Hot water under pressure would erupt on the surface. A lot of this would depend on the rock the water is flowing through. Very porous rock would not hold onto the pressure like a thick layer of sense rock.

Could such an event cause the two craters that have deep craters with in them;

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Check out the two small shallow craters with deep craters directly in there centers. Seeing craters within craters is not unusual on Mars or even the Moon or Mercury. What caught my eye is these two craters sharing a lot in common. I don’t think it is a coincidence. These two craters had me perplex, but your insight might just explain them. Maybe they are extinct geysers.

Mars is an interesting planet with lots of surprises. As a geologist I see signs of water all over the planet. There must be an ocean worth of ice under Mars surface so I tend to disagree with a lot of Nick’s hypothesis. Nick is right about one thing. Mars is not the Earth. Mars is it’s own planet. I do like Nicks different point of view. It is always good to take a different path on the same problem.

As always we need more data. What we really need is a permanent human presence on Mars. I do hope that once the human race sends people there, we’ll have people there until the end of time.