Mike Reynolds forwarded an interesting article about Snow pack providing the pressure for Mars water to exist and form gullies. If this is true, since snow (sublimated frost) can form anywhere on Mars, there ought to be more gullies in the lower elevations (say, the rim of the Hellas Basin) than in the higher elevations (Tharsis plateau), at similar distances from the equator. This is because the pressure on Mars is near the Triple Point pressure, and a similar amount of snow in either place ought to produce more gullies in the place where the air pressure "helps" most. There are some assumptions here, and certainly the gulley system shows a wide range of ages. One must not be too hasty in jumping to conclusions, but a superficial glance does show more larger gullies at lower elevations. A precise count and control for age from crater counts may be helpful. Further, there should be some variation in the alteration of same-age Martian meteorites originating from high elevation on Mars to low elevations. As the Morroccans busily increase the sample (and non-Morrocans like Mr Verish :), we will see.
Francis Graham __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - forms, calculators, tips, more http://taxes.yahoo.com/ ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
