[X] My Assistant

[Bill Harris]

It looks more like a collapsed region which has lost ground ice which seems to be presents in all Tharsis Montes.

The "Tharsis Montes" are shield volcanoes. Lava flows. Where does this ice come from?

[Harkeppler]

The "Tharsis Montes" are shield volcanoes. Lava flows. Where does this ice come from?

Resublimation of water vapor at high, cold places like a cold trap. In 1985 there was an interesting idea that the Tharsis Planitia was situated for a while at one of the both poles:

1985.P Schultz P.H. Polar wandering of Mars. Scientific American 253, pp. 94-102.

The main calderas of the large vulcanos seems not to have been ever something like the Hawaian "lava sees". They are only sunken depressions. No pots of molten stone, more an uplift of the original crust with layers of vulcanic ash, lava and - ice. The main vulcanic activity was seen more at the flanks.

If You have a look at the "Dena"-site (attachement), You see a widely collapsed landscape at the flanks of Arsia Mons. This does not look like the work of lava tunnel systems. Furthermore, the Dena-Depressions are at the floor of another larger depression - we have a multi-stage and multi-layer collapse telling me that there are several layers of ice gon away more or less effectively.

Harkeppler

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[Harkeppler]

This may be of interest:

An Article from 2004 reflects some informations to water and ice at the Tharsis Planitia. It does not look completly dry...


Enhanced Water-Equivalent Hydrogen on the Western Flanks of the Tharsis Montes and Olympus Mons: Remnant Subsurface Ice or Hydrate Minerals?


http://www.lpi.usra.edu/meetings/lpsc2004/pdf/2011.pdf

[Harkeppler]

These are not the features usually called gullies; the conventional view is that they are dry dust avalanches and do not involve a liquid. See, for example, Rob Sullivan's abstract http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1911.pdf

The best is the last sentence of that paper:

"Modeling is underway to determine if avalanche velocities and dynamics are sufficient to suspend dust during entrainment as the avalanche front moves downslope."

Maybe "if"... maybe not...

The dark streaks and fans looks very sharp and structured. There are at least four possibilities: 1. the dark material is the underground and the light toned one has been removed. 2. The dark material has been added. 3. The dark material is light toned material getting soaked. 4. The dark streak is a mix-up of the light toned maybe by turbulent gas.

Harkeppler

[djellison]

I am sure that there must be an ambient temperature and an sufficent pressure to allow the spilling of a fluid.

How sure? Have you done the leg work? Found typical atmospheric pressures at that altitude, looks at phase diagrams. Remember - even at lower altitudes we're working in a very thing part of the phase diagram that allows water only over a very small temperature range.

And - if, as you say, there is so much water here - where is the minerological evidence for it?

It's easy to go 'looks like water'. It's very hard to make a water tight case for it. You're a long way from that.

Doug

[Bill Harris]

Doesn't work that way, Hark. You've got a shaky theory supported with suppositions...

[mcaplinger]

The best is the last sentence of that paper:

"Modeling is underway to determine if avalanche velocities and dynamics are sufficient to suspend dust during entrainment as the avalanche front moves downslope."

That abstract is seven years old, so you may want to follow where the research went after that. It's not like you were the first to notice these features.

[J SHO]

I am posting this MRO picture, because it appears to have both the dark streaks and a cave in the same image. The cave appears at the bottom portion of the image, and looks to be pretty large. It appears that the top layer of dust appears to have been removed around the opening of the cave. Very interesting picture!

http://hirise-pds.lpl.arizona.edu/PDS/EXTR..._RED.browse.jpg

[ugordan]

That doesn't look like a cave to me, more like very dark dust on a sunward facing cliff?

[J SHO]

I guess it could be dark dust, but it looks to me that the top of the cliff is overhanging, no?

[Harkeppler]

Thats very interesting!

Obviously, the dark patch looks much the same in a Mars Global Surveyor Image.

http://www.msss.com/moc_gallery/e01_e06/im...2/E0202590.html

There are a few new streaks in MRO imagery compared with this older picture.

Coordinates are

11.3 ° Longitude 181.0° East /179° West (used for MGS imagery)



See also Mars Odyssey imagery for an overview


http://themis-data.asu.edu/img/I18416013.html
http://themis-data.asu.edu/img/I17193052.html








Harkeppler

[Harkeppler]

As I see yet: there is a second "dark cliff" in this picture:

http://www.msss.com/moc_gallery/r16_r21/im...8/R1800437.html

What do we see here? Is that a natural bridge? Monument valley on Mars?

The formation is situated a little more east with respect to the primary one.

Some similar knobby hills in the vicinity:

http://www.msss.com/moc_gallery/e07_e12/im...1/E1101435.html
http://www.msss.com/moc_gallery/r10_r15/im...2/R1204047.html
http://www.msss.com/moc_gallery/r10_r15/im...3/R1303642.html
http://www.msss.com/moc_gallery/r10_r15/im...1/R1102555.html

Harkeppler

[Elias]

You can find some relevant NIAC (NASA Institute of Advanced Concepts) studies & material in the following links:

Study 1

Study 2

[Guest_jumpjack_*]

Sorry, newbie question: MGS got lost months ago. So, are these images just been "discovered" after probe's death? I mean, we had them, but we didn't examine them yet?

[edstrick]

Small features in tens of thousands of fairly large pixel-dimension images.. did she reach 100,000 images?..1024 x 4000 is not unusual.. they can be LONG ribbons take a lot of cumulative looking to spot. And the researchers: Professors, postdocs, grad students, civil service scientists... have a lot more to do than just oogle images all day.