Sinkhole North of the new water flow

Author Message
Robert J Crowley

PostPosted: December 7, 2006 7:40 PM 

Stereo images like the stereo pair of this week's (December 5, 2006) comparative images from the Mars orbiter, showing what appears to be flowing liquid of recent origin, are extremely sensitive ways to detect and spot spatial and temporal changes.

This is indeed the case with the recent images! Not only can we see an apparent flow, but to the North of the crater wall, there is an apparent sinkhole, also of recent origin. The fact that this geologic feature is in direct line with what might be the origin of the recent flow is extremely interesting. Here is a case where stereo imaging reveals a large apparent change in surface geology. I do not think this to be a shadow or other artifact.

I have not read or heard of any previous comments on this exciting, easily observed feature.

Robert J Crowley
Soundwave Research Laboratories, Inc
Ashland MA

jdub Author Profile Page

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PostPosted: December 7, 2006 8:36 PM 

Is this the feature you're looking at?

Robert J Crowley Author Profile Page

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PostPosted: December 7, 2006 8:51 PM 

Yes it is.

I see that the sun angle is not exactly the same in both images. Stereo viewing of the two images indicates spatial changes consistent with the direction (peaks of the ridge appear closer for example) of the overall scene - in this case, a depression. It appears to me that the North East edge of the feature is the area of most change.

The feature is very prominent in the stereo view of this image pair you have posted and also the one I have posted and commented on at

Ben Author Profile Page

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PostPosted: December 7, 2006 9:36 PM 

Robert: I think any difference in the two images is due to contrast and since the ground here is most likely frozen, I doubt a sink hole could occur. Probably just a small impact crater.

jdub Author Profile Page

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PostPosted: December 7, 2006 9:45 PM 

The roughly oval feature appears to be in positive relief. It could be sitting in a shallow depression but it's hard to tell. I'm not sure I see the sink hole.

Robert J Crowley Author Profile Page

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PostPosted: December 7, 2006 10:05 PM 

Hi Ben

Why would only that area exhibit the contrast difference, and not the surrounding areas?


I know you have better stereo viewing than I have. It looks depressed to me especially in the wide angle images. A better stereo pair would consist of two recent images with small angle differences. Those would probably better resolve the present contour and tell us if it is up or down.

Still, that area appears to be changed in a fundamental way. If the feature is indeed a contemporary impact crater, then ejecta and seismic disturbance could have perturbed subsurface ice/liquid water and the surrounding substrata. I'd think that these two new, contemporaneous features ought to be at least considered in context with each other.

dishman Author Profile Page

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PostPosted: December 8, 2006 4:44 AM 

I agree with Robert. If you look at the right image you can see that there is definately a slumping effect not present in the left image. the shadows in the left image are deeper than the right. However the right image shows an enlargement in the "sinkhole features" size. Also there is a fuzzy outline that is not there in the left image.


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PostPosted: December 8, 2006 10:02 AM 

Let me try an animation of those two pics, with contrast adjusted:


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PostPosted: December 8, 2006 10:13 AM 

This is a close-up (200%) in false 3d:

jdub Author Profile Page

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PostPosted: December 8, 2006 9:16 PM 

The circled feature, probably a rock outcrop, projects. The shallow depression surrounding it could be due to wind erosion in that it sits in a trough which would effectively direct winds through this area.

MOC stereo pairs can suffer from a lot of problems because they're captured at different times. Among them are illumination differences and real surface changes, both of which are seen here. Inconsitent lighting causes visual ambiguity and the illusion of shadows is caused by wind deposited dark fine material (right image).

My 2 cents anyway.

jdub Author Profile Page

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PostPosted: December 9, 2006 2:29 PM 

You guys might find this interesting. Keith Laney had this very crater pegged years ago for for ice and a subsurface aquifer. He even talks about possible sink holes.

Robert J Crowley Author Profile Page

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PostPosted: December 17, 2006 12:01 AM 

I was unaware of Laney's observations and after looking at the images on his site, I am not sure that the features he shows are the same, though I assume they are from your comment.

The graphic on his site, taken from NASA, showing the horizontal stata relative to the crater wall, seems to me, oversimplified. Such a perfectly laminar stratification would only be consistent with a mechanical excavation, or river channel erosion, whereas an impact crater might exhibit considerable distortion and deviation from the horizontal.

I'd expect that distortions of the horizontal substrata would occur during crater formation, resulting in additional wall dams parallel with the sloping crater surface. These would be consistent with a radial compression of the surrounding landscape, which I believe can be seen outside the crater. The compressed folds might be quite deep, allowing subsurface pools to form behind them, or perhaps even connecting multiple layers of ices and/or liquids.

Robert J Crowley
Soundwave Research Laboratories, Inc
Ashland MA USA

rad-dog Author Profile Page

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PostPosted: December 17, 2006 1:39 AM 

In your stereo image there is a very bright spot just below and across the ridge from your circled feature that looks like a small depression. The spot looks like it could be filled in with snow or ice. Is ther any way to magnify shis spot?


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PostPosted: May 25, 2007 8:15 PM 

You have a beautiful site. looks good under music debaser lyric rogue wave

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