[RightWhale]

Thanks for the image. The caves are ice-formed tubes that have broken through to the surface and the ice evaporated. There are many examples on Mars, some with some ice still in them.

[Candor7]

Yeah. Some believe them to be lava tubes but the geology is wrong. I remember seeing a color photo several years ago of an unmelted ice tube exposed to the surface, found by an amature investigator. Nasa was mute about that one.

It looked like a glass structure , segmented like a worm.

The ice must melt quickly once exposed to the surface, and there must be a gusher for a while and the overburden collapses into the drift. Interesting stuff. Nasa is obviously investigating outpost sites or how to select an outpost site, but by the time they get there years hence, the water in these tubes will likley have disappeared.

Context Images for these strips: Left MOC Frame No. R11-02729, Right THEMIS-VIS image No. V01028006 & MOC Context locations

The mountain photo on the right could be a lava tube series running from the caldera down to the base of the volcanic structure. That one looks like a caldera cave, not a water /ice tube.

The photo on the left is a pit, but it has what looks like water born sediment residue on the bottom. Maybe partly filled with water at one time?

I wonder how much seeps down into the substrata as opposed to evaporation?