On the Road Again - volume 5 - Page 18

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Author Message
Ben


Posts: 2270

Reply: 341



PostPosted: February 25, 2010 6:24 PM 

Is it possible that some of the small,older craters have eroded "ejecta rays" buried beneath the dunes or is this an unusual phenomena?

Barsoomer


Posts: 344

Reply: 342



PostPosted: February 25, 2010 7:27 PM 

Horton, I wonder if you could do a colored 3D of this. Especially the Matterhorn-like rock in the foreground. I think it suggests that when the coating erodes away, it occasionally leaves behind something very like the berries-on-stems (and/or other things on stems).

LWS


Posts: 3062

Reply: 343



PostPosted: February 25, 2010 10:03 PM 

Hi Serpens; Would you include some of the insights of NASA staffer, Everett Gibson, an astrobiologist, in the JPL model. Here's one of his papers which I'm certain you are aware of, which strongly argues for current life on Mars beneath the surface.

here

There's also a powerpoint presentation that he gave to a big meeting about two years ago and which I'm trying to relocate on my computer that was even more explicit in his views on Mars life.

Winston

serpens


Posts: 169

Reply: 344



PostPosted: February 25, 2010 10:10 PM 

Stuart Atkinson actually posed an excellent rendition of this. (I have a not so hidden agenda in linking this as I want Hortongheardawho to have lots of time to develop more of his addictive x-eyed images). Very Happy
http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=20827

Barsoomer


Posts: 344

Reply: 345



PostPosted: February 25, 2010 10:53 PM 

Thanks Serpens, I did see Stu's color rendition, but I still want Hort's 3-D x-eyed version. Pretty please! Horton also has this uncanny knack for making pancam views that have nearly MI visibility of tiny features.

Winston, I read that paper you linked. One thought I had is that if life has persisted on Mars for billions of years, there would be a tremendous evelutionary advantage in using the global dust storms to disperse spores, so I would expect some use of surface resources even if life is primarily underground.

hortonheardawho


Posts: 3465

Reply: 346



PostPosted: February 25, 2010 11:04 PM 

Here is the L234567R357 3D shadow enhanced version of reply 342. The crust in 3D is quite weird.

I will redo when all the filters are downinked.

Barsoomer


Posts: 344

Reply: 347



PostPosted: February 26, 2010 12:56 AM 

Thanks very much, Horton! There certainly is a lot of weirdness there! Tangled messes of loopy crust. Pieces of smooth flat crust seemingly levitating above the rock. (Obviously they are supported, but how?) Stems pointed in every direction. Some kind of object resembling a brick in what looks like a cavity down behind the big rocks.

Wow!

Mizar


Posts: 692

Reply: 348



PostPosted: February 26, 2010 11:27 AM 

A section from Horton's image re#346. Seems really levitated, but even on Mars it's still impossible. Wind sculptured, with almost no other forces to break the hidden remaining thin delicate support stalks seems reasonable to me. Weird feature indeed.


Ben


Posts: 2270

Reply: 349



PostPosted: February 26, 2010 11:50 AM 

The reply 342 image appears to support the fill is comprised of laminations which indicate more than one phase of deposition.

The lack of laterally continuous fill layers(ie ragged patches) may not be due entirely to erosion but may represent the way the fill was deposited in the fracture.

Softness of the(younger?)bedded host rock,
at this locality, is demonstrated by its erosional removal( gap) between the bedding and the fill.

BTW, I have never said the fill does not involve a biological component; and have been most concerned with the deposition.

Barsoomer


Posts: 344

Reply: 350



PostPosted: February 26, 2010 12:34 PM 

Maybe it's time for another MER press conference to give us some inkling of the team's reaction to the unique finds at this crater. I would love to hear what discussions are going on at the SOWG meetings.

LWS


Posts: 3062

Reply: 351



PostPosted: February 26, 2010 1:22 PM 

Ben;

Appreciate your comments at #349.

last night I came across some info on impact melts that had me very surprised. I think it was a NASA info paper that indicated that the heat in the vicinity of an impact could last at an enhanced level for 1,000's of years. I can't locate that paper this morning and I would be grateful if any of the geologists on the board could assist in clarifying if heat levels could remain elevated for so long. I had thought that changed heat levels etc, were likely to return to ambient martian levels quite soon after the impact but the paper suggests otherwise.

If a comparable situation exists on Mars and there is ice just below the surface then it might make it just possible that impacts could be a major mechanism for dispersal of any putative life that might exist under the surface.

If, let's say, a small impact like the one at Concepcion could liquify ice in and around the crater and the heat is retained for several weeks or even months, then there might be the possibilty that putative dormant spores could germinate and occupy virgin rock surfaces before mars ambient conditions prevailed again. They would then form resting structures, be frozen, get brittle, drop off in the soil, be covered by the dust, get indurated into rock and then get brought back to the surface by the next impact a few million years later.

Sounds far fetched, but could this putative cycle be part of what we are seeing on the rocks at concepcion?

Winston

Barsoomer


Posts: 344

Reply: 352



PostPosted: February 26, 2010 1:24 PM 

If the flat "levitating" portions of crust are wind-carved, shouldn't they be more streamlined? They seem to have a complex texture including wrinkles. Also, why wouldn't the wind have carved away the tangled loopy portion of the crust near the front of the rock?

I had hoped to see an x-eye closeup of the conical rock at the bottom-left corner of the original pancam image, which I had called "Matterhorn" because it resembled the well-known Swiss Mountain. It seems to have stems that support things that are more complex than the spherical berries.

Barsoomer


Posts: 344

Reply: 353



PostPosted: February 26, 2010 2:45 PM 

The flat crust that is overhanging the edge of the rock may provide a lower bound on the amount of erosion of the host rock that has taken place. Presumably the overhanging part was originally above now-eroded rock. I'm not sure what the scale is in the image, but as a WAG, it seems about 10 cm of rock has eroded away.

Ben


Posts: 2270

Reply: 354



PostPosted: February 26, 2010 3:14 PM 

Winston; I find no fault with your concept except I believe the fill layers required possibly hundreds of years to accumulate and I doubt that impacted rock could have stayed warm that long.

Why not apply the same idea to warm ground water that rose to near the surface along old dessication cracks allowing the spores to flourish , deposit the layers and then become dormant when the ground water dropped.
Impact then ejected the intact, fragments we see now Smile

Barsoomer; The fill layers appear to be harder than the soft host rock so gentle winds over a short time haven't resulted in much erosion or change in them.

I believe the texture of the fill layers is due to their mode of accumulation( precipitation out of a liquid ).

THink of all the weird accumulations on surfaces in caves.

Barsoomer


Posts: 344

Reply: 355



PostPosted: February 26, 2010 4:40 PM 

> ... texture of the fill layers is due to their mode of accumulation( precipitation out of a liquid ).

The crust looks to me like it was sticky or gooey when it was mobile. I would think it hardened directly from a viscous fluid form rather than precipitating out of a clear liquid. What do you think?

> THink of all the weird accumulations on surfaces in caves.

Due mainly to biological activity?

hortonheardawho


Posts: 3465

Reply: 356



PostPosted: February 26, 2010 5:42 PM 

sol 2166 ( Feb 26, 2010 ) L257 5x1 pan:

the original size is a 2X version for those of you who wish to crawl around in this area on your hands and knees.

Barsoomer


Posts: 344

Reply: 357



PostPosted: February 26, 2010 5:45 PM 

According to this paper, the estimated erosion rate on Mars in the current Amazonian period is about 10-2 nm/year.

At that rate, it would take a billion years to erode 1 cm of rock. How do we square that with the amount of erosion we seem to be seeing here? Even if the rocks are much softer, could that account for such a difference?

John


Posts: xxx

Reply: 358



PostPosted: February 26, 2010 5:46 PM 

I posted a few days ago about dessication cracks in my back yard. Now, Barsoomer I admit, I am no HYDROGEOLOGIST, but have made some observations. I was in the boiler room doing a bottom blowdown yesterday. A few weeks ago we did a boiler treatment with phosphate powder. It left mud on the floor. The mud dried and left a surface riddled with cracks. Larger cracks and polygons occurred where the dried mud was thickest, graduating in an even manner to smallest there the mud dried thinner. I observed the blow down water creeping across the area of mud. Within SECONDS, the cracks closed, leaving only a small indication of the cracks. This left me to look up (for "simplicity"), expansion and hydraulic pressure of wetted clay. Quite an arcane science, I found. NOW, considering cyclic moisture events, either from wicking or percolation, AND periods of dessication, whatever fills the cracks be compressed. If this happened on a cyclical basis, it would result in a structurally laminar fracture fill.

Ben


Posts: 2270

Reply: 359



PostPosted: February 26, 2010 8:01 PM 

Check this out for differential erosion.
They are called "hoodoos"

[link]

LWS


Posts: 3062

Reply: 360



PostPosted: February 26, 2010 10:52 PM 

Hi Ben;

Getting back to the orientation of the fill in relation to the bedding planes of the rocks. In the absence of an official census, I've had a very unscientific look at the "fill" or "crust" and their orientation on the concepcion rock surfaces. It looks as if the fill is predominantly found on surfaces vertical to the bedding planes. However, they are a significant number of these crusts or fills that are on surfaces parallel to the bedding planes.

The consensus here and at UMSF appears to be that the crust material cannot be classical impact melt and thus is almost certainly fracture fill. But, to my mind the fracture fill explanation is not totally satisfactory as it seems inconceivable that so many rocks (most rocks have evidence of the crust material on some surface) ejected from the crater at impact would have had preexisting fractures prior to the impact event. Shouldn't the soft evaporite rock be expected to have more fractures on landing on the crater edge than existed before the impact? If the crust material exists on these new fractures formed after impact it would seem to suggest that the crust was formed after the impact.

Wouldn't the combination of crust on surfaces parallel to bedding planes as well as also probably being on post impact surfaces, as well as curving over edges of rocks, suggest that it is quite possible that they formed after the impact and not as fracture fill prior to the impact?

Is there any way from a study of the images to estimate the cracks or surfaces which are likely to have been made after impact as compared with those that were likely pre-impact? Could general NSEW orientation of the surfaces at present be of any use?

Winston

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