I've returned from a weekend of being cloistered with several differenct writing projects (e.g., the upcoming SpaceDaily collaboration with Nick Hoffmann, a few papers being submitted to journals, review of a couple of papers and one Ph.D. dissertation, etc.) and find several interesting disccusion threads below.

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In response to Jill England's post at
http://www.habitablezone.com/space/messages/13685.html

Jill England wrote:
The Mars Society power point presentation of Efrain, Jill, and Harry's paper has been installed at http://www.eskimo.com/~jill/marssociety_presentation.htm

Alex writes:
I'll admit, yours and Palermo's model is interesting. Though I've followed the issue of the dark streaks since they were first identified in the MOC NA imagery and find the prevailing explanation (dust avalanche scars revealing low albedo substrates) to be convincing, I'm open to new ideas. I do know that Rob Sullivan (who has tracked this issue as closely as anyone) has a fairly detailed paper in press with the Journal of Geophysical Research covering the dust avalanche scar model. BTW, is there a PDF version of the Mars Society presentation available? If possible, I would very much like to download the file, print it, and read a hardcopy during my "free time" ;-)

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In response to Efrain Palermo's post at:
http://www.habitablezone.com/space/messages/13667.html

Efrain Palermo wrote:
Is water behind these proposed seepages? I cannot state this as a fact, but...I would like NASA/JPL to focus some attention onm these flows in their upcoming Odyssey mission and settle the question.

Alex writes:
As I responded to Jill England above, your model is indeed interesting, though it's fair to say that I'm skeptical. However, I am amenable to reading more details. As for 2001 Mars Odyssey and any investigation of the "dark streaks", the only instrument that might have any value at all is the THEMIS IR with ~100 m spatial resolution for mineralogic studies (the THEMIS VIS regional context imager supplied by MSSS probably has too low a spatial resolution for useful data). On the other hand, the proposed high resolution imager (HRI) for the 2005 Mars Reconnaissance Orbiter (MRO) mission is projected to have cm-scale resolution and would prove extremely useful, especially for morphological studies. Personally, I am interested in the clastic/particle debris sorting mechanisms in these and other types of flows and margin thicknesses at the distal ends.

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In response to Peter Ness' post at
http://www.habitablezone.com/space/messages/13644.html

Peter Ness wrote:
Does anyone have any psychological problem with the suggestion that
meandering rivers and canyons can form on Mars now, and without any
large quantities of water (h2o) - provided we can clearly show:
1) images with meanders being formed
2) images of canyons that may have been formed quite recently in
martian history
3) one or more mechanisms where these this could happen

Alex writes:
I do not believe I have any "psychological problem" with your suggestion, but call me old-fashioned - I would feel more comfortable seeing some "data." Indeed, I would love to see the details of your model, especially your identification of the erosive fluid(s) to which you attribute the "...meandering rivers and canyons...form[ing] now..." I would only note that the proposition that "rivers and canyons" on Mars may form "without any large quantities of water" is not really novel. Carr and Malin, amongst others, have put forward the subsurface sapping model for many years. At any rate, I'll echo (actually paraphrase) what Nick Hoffman said: "I'm skeptical of your thesis, but good luck getting it published."

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Alex R. Blackwell
University of Hawaii