Saturday, December 16, 2006

More on the Martian Sinkhole


Aha!

I'm not (totally) crazy.

Check out this site and scroll to the third image down, showing the same crater I have been talking about. It turns out that Keith Laney spotted the very same feature on Mars that

I said had changed recently.

I believed it was a sinkhole since it is close to and above the area of a recent outflow of liquid. Laney suggested - six years ago - that it was filled with ice. Indeed!

1 comment:

Bob Crowley said...

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.