Thanks for the link to the image. Notice that the two streaks on the right seem to widen as you move from the point of origin.
I have argued that this characteristic of some *wind-blown* streaks on Mars is indicative of material being vented:
Newsgroups: sci.astro, alt.sci.planetary, sci.geo.geology
From: rgregorycl...@yahoo.com (Robert Clark)
Date: 13 Feb 2004 07:03:49 -0800
Local: Fri, Feb 13 2004 11:03 am
Subject: Re: Active volcanic vent on Mars?
David Knisely <ka0...@navix.net> wrote in message <news:O7_Wb.96$FO.email@example.com>...
> Robert Clark wrote:
> > Take a look at a hires image on this page:
> > Portion of Valles Marineris.
> > http://sci.esa.int/science-e/www/object/in...fobjectid=34528
> Nope, sorry, its no volcanic vent. Its just a small dark albedo feature which
> is underexposed enough so that you can't see the underlying topography. It
> shows up in the MGS Atlas pretty well as a teardrop-shaped darker spot, and is
> also visible in the old Viking MDIM images. Clear skies to you.
Take a look at a hires image on the page, in either JPEG or TIFF
The dark material gives the definite appearance of emanating from the
crater. It also has a key characteristic suggestive of a geyser or a
vent: the dark material is light right next to the vent but heavier
further away. This is suggestive of material being thrown up with some
velocity and then coming back down some distance away.
Another key characteristic of a vent or geyser I consider to be the
fact that the origin is quite small compared to the widest portion of
the dark area. If this was just a wind blown deposit it wouldn't widen
out to this degree. It remain more or less the same width as the
A noted Valles Marineris expert has argued for recent volcanism in
More on RECENT(?) Dark Volcanic Patches in the Valles Marineris, Mars
Lucchitta, B. K.
LUNAR AND PLANETARY SCIENCE XVII, PP. 496-497. http://adsabs.harvard.edu/cgi-bin/bib_quer...LPI....17..496L
Note that streaks on slopes also widen as you move down slope but these are gravitational driven rather than wind driven as in these cases.