Ausonia Mensa Gully: Ground Water or Snow Pack?

[voyagerwsh]

Two dominant models to explain the likely cause of martian gullies have been proposed, i.e. ground water or snow pack. <br /><br />One model (1) was proposed by Michael Malin et al. as ground water or aquifer repeatedly outburst with water/ice and debris as called ice dam break running down slope which would carve the soil and form gullies.<br /><br />In Phil Christensen's snow pack model (2), Dr. Christensen explains the gullies was formed by melting snow pack which was accumulated durind 50,000 to 500,000 years of time span.<br /><br />Interestingly, can ground water explain origin of the gully in 3,700 meters elevation on Ausonia Mensa? Or Snow pack model is gaining upper hand to the proposed martian gullies formation. I would favor snow pack model which may have better explaination on this gully formation in that groundwater or aquifer would probablely not dwell on the 3.7 km elevation.<br /><br />(1). http://nssdc.gsfc.nasa.gov/planetary/news/mars_water_pr_20000622.html<br /><br />(2). http://www.geotimes.org/mar03/WebExtra031403.html<br /><br /> <br />

 

[JonClarke]

I would agree. the snow pack model is consistent with what we know about the extreme martian climate cycles and explains the glaicer like features associated with some of these gullies, whether residual mantling deposits (some with flow and fracture features suggesting semi-plastic behaviour) or moraine like risdges at their lowe slope ends. I have also found the actual mechanisms for maintaining and regenerating the hydrostatic pressured need to cause the water outbursts difficult to imagine, seeing that the hydrological cycle on Mars appears dormant.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[yevaud]

I always did wonder about that. What sort of sudden temperature increase (let alone why) could cause some of the catastrophic outflows that are seen? <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[voyagerwsh]

To enhance Jon's observation on the martian climate cycles, we may consider the orbit tilt degree of Mars. At 15-40⁰ tilt of its plane, Mars may have very different climate cycles during its entire 4.5 Gys history.<br /><br />With Mar's angle tilting at 40⁰, polar cap ice could redistribute the martian hydrolic mechanism in a dramatic way, also would increase the temperature of sun facing regolith of the perihelion hemisphere.<br /><br />

 

[JonClarke]

I think the large outflow valleys - like Mangala, Athabasca, Ares Valles for example, have different origins. The present, as far as we can tell, sudden catastrophic outflows that require largescale melting of the presumed cryrosphere. Several processes have been suggested, all all may be right, given the fact there are many different outflow channels of different ages. The proposed causes include local volcanic heating, local impact heating, and global warming through impact induced climate change. Athabasca Vallis is almost certainly related to volcanism, and is less than 20 Ma.<br /><br />Hope this helps<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[yevaud]

Most certainly, and thank you. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[voyagerwsh]

Gullies on Lunar crater, Dawes, resemble the martian crater gullies in high resolution morphology. Most will agree with the Dawes' gullies should have formed by waterless land slide or dirt avalanches not water, according to Gwendolyn D. Bart of ASU.<br /><br />The Lunar gullies would strengthen the camp of dry formation of martian gullies.<br />------------------------------------------------------------------------<br /><br /><br /><i>"If the dry landslide hypothesis for the formation of martian gullies is correct, we might expect to see similar features on the moon, where there is no water," she (Bart) said. "We do."</i> <br /><br />Link<br /><br /> <br /><br /><br />

 

[JonClarke]

It is important not to assume that one process explains evcerything. Dry flows will explain some gullies, but not ones that have meanders, for example, which (as far as I know) require liquid water. Max is a complex place and we should expect many processes to have operated.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[voyagerwsh]

I agree with Jon that many martian gullies would require liquid water to carve them, like channels or meanders as Jon mentioned above. None all gullies would be explained only by wind and dirt avalanches, many would suggest liquid water as the mechanism. <br /><br />The wind erosions suggested by Treiman would not apply to gullies on Dawes crater on the moon, but as Bart suggested on ASU newspaper, many martian gullies were formed by either water or dry avalanches. It just happened that gullies can be formed on dry and almost non-atmosphere existence celestial body. Therefore, we might find gullies on Mercury craters?

 

[voyagerwsh]

If liquid water should suggest the formation of martian gullies, then liquid water could exist on or near the surface of present day Mars. <br /><br />A contemporary gully was imaged by MOC.<br /><br />Link

 

[bonzelite]

in all fairness, the pre-gully features, those that can or may be assessed to be "already there," do not match the later photo in patterning. <br /><br />i will provide this, though: that prior "gullying" did happen, was buried beneath wind-blown regolith over time, and then "re-gullied" by a mechanical process that rendered a gully down a similar, but not the same, path. the process is evident in surrounding "buried" gullies, soft linear features evident in the surrounding dune-field. remains of past events.<br /><br />whatever mechanical process acted upon that specific slope area "re-gutted" or "re-gullied" the slope, as the process may have happened again and again and again, not quite carving the same trench, but following the same or similar path. because my hypothesis is about multiple mechanical events over the same slope, i will propose that the mechanical "culprit," be it fluid or sand, happens semi-regularly. <br /><br />the gully is, then, <i>recent and not merely a region of selective exhumation, but, instead, an area gone over again by the same process to render a new specific tracing path, but following a general past route. the gully is new.</i>

 

[JonClarke]

I can't see this being an exhumed gully. Look at the context - it is on the crest of a dune. It is unlikely to have been old gully there beforehand. This is a new feature, I am sure. the real issue is, what caused it?<br /><br />Dry particle flow? Maybe, but I don't link dry particle flows form such nice tributaries, nor do they meander. I suggest melting of buried snow, as suggested by Mary Bourke link<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[bonzelite]

i am of a similar mindset and assessment as JohnClarke. in many cases where sand or wind is declared a culprit, the trace signature of the flow pattern resembles a fluvial mechanism. i do not rule out sand or wind, but the gully carved in the photograph is very, very deep and crisp, terminating in fan structures as you would see in water erosion --sculpted by something of a dynamic fluid (this is but one of many, many pictures of gullying and/or sediment carrying).<br /><br />being that mars is replete with terrain softening, as the surface appears (at least in part based upon mounting data), to be a vast desert tundra, melting of pack ice is the most, as of yet, viable explanation. i am inferring at this point in the game that much of the martian regolith is an aggregate of ice, snow, and dirt. <br /><br /><i>this further takes my mindset far and away from a recent press release that the gullying on mars is created by sand, as is seen on the moon. furthermore, the pictures of said moon strutures, in my professional assessment as a visual artist, do not template the martian structures. if anything, the martian structures should template the lunar structures. <br /><br />furthermore, being that the highly softened and eroded lunar gullies are of sufficient age, who is to say that fluvial dynamics were not also a culprit? shattering the idea that liquid is impossible on the moon, as well? we do not know about the lunar past as it may have really unfolded. but that is another topic entirely...</i>

 

[voyagerwsh]

Borman, that link is not working.

 

[bonzelite]

that is very compelling evidence. i'm on the fluvial bandwagon, but the dry flow data is compelling. <br /><br />what we would need to do is literally place sensors and equipment at the exact locations of these gullied areas, dozens and dozens of arrays of sensors with 24/7 surveillance of the slopes and rims and outcroppings. we'd need a fully appointed geology and photographic suite of ethernetted "nodes" of live video surveillance, for years in perpetuity, conducting geology and meteorology at each site, constantly. <br /><br />this way, we'd know how they got there. we DO know the features emerge semi-regularly. so we wouldn't have to wait that long to have some live data. <br /><br />this brings to mind a parrallelling issue: why in hell don't the rovers have live video feeds? i'm not talking snapshots and stuff, i'm meaning literal surveillance, with timecode and the whole deal. this way, even the slightest movement on the surface could be observed in live action detail. not just with single framed images. mars is the perfect place for live video feeds, as it has a dynamic atmosphere and surface. we may be able to see some of the processes, LIVE, that sculpt it's surface. it'd be an invaluable and off-the-shelf tool. so why in bejeezus haven't they done this yet? they have such stuff at every 7/11 store and bank. but not on mars? why not? it would probably OVERNIGHT literally solve a lot of mysteries. years of guessing and headaches would be forevermore <i>gone.</i> <i>what's the problem? where's the video feeds? all of this technology and no reality tv yet? hello NASA. get a damn clue.</i><br /><br /><br />

 

[JonClarke]

I could not find anything on Bernoulli fluids composed of dry particles, so I remaind very sceptical that they can form true meandering flows. In my experience granular flows on both land and water form remarkably straight deposits and erode slope normal gullies.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[voyagerwsh]

We found few S-shape narrow channels meandering down slope in the Terra Sirenum gullies which unlikely be explained by sand or dirt avalnaches but fluid mechanism.<br /><br />Link

 

[voyagerwsh]

Certainly, dry dirt landslides and dust avalanches could explain the gullies and channels in lunar crater Dawes in that liquid water would not possible exist on the surface of the moon. <br /><br />I would suspect dry dust could reveal the meandering S-shape deep channels on martian craters, especially liqiud water could exit under martian condition, i.e. atmospheric pressure />6 mini bar or above triple point of pure water. Liqiud mineral water (Mg, S, Ca... mixtures) can even have much lower triple point on Mars. My guess work would suspect ground ice melt in some occasions or places and carved the Mars crater gullies, only the energy sources of melting the ground ice are missing in that many gullies are in opposing sun-facing propotion of many craters. <br /><br />I agree that the much more debates over the creation of martian crater gullies would continue for sometime.

 

[bonzelite]

what about the termination fans? <br /><br />video capture of a gully would end these debates instantly. <br />

 

[JonClarke]

"video capture of a gully would end these debates instantly. "<br /><br />No it would not, unless you happened to catch them in action, as it were. So far, with one possible exception, pointed out by Nick Hoffman, they appear to be inactive over the period of observation. This should not surprise us. A much better way is to monitor individual gullies for change over a long period of time. This is what is being done now by MGS and soon by MRO.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[bonzelite]

<font color="yellow"><br />No it would not, unless you happened to catch them in action, as it were.</font><br /><br />of course! that is the whole point!

 

[JonClarke]

There are thousabds of gullies on Mars. Which ones are you doing to monitor? It may be thousands of years between flow events. What system is going to monitor the gullies for this length of time?<br /><br />It is far better to check a representative sample of gullies every few years from an orbital systems and see if there is any sign of changes. This is what we are doing now. There is no need for continuous video footage. <br /><br />For specific events - willy willies, eclipses, wind gusts we already have video or near video quality footage from the MERS and Pathfinder.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>