Earthlike Mars? Options

[glennwsmith]

All, I know this isn't the right place for this post, but I've looked around and can't find an appropriate, current UMSF forum (Doug, perhaps you could give me some guidance on establishing such) -- so here goes: I think a [the] new paradigm for Martian geology is rapidly coalescing, namely, that Mars is very much like the Earth in terms of the preponderance of water -- except that it is all frozen, and covered under a thin layer of dust/regolith! See, for example, this article:

http://www.skyandtelescope.com/news/41995902.html

Hence the "seepages" found in crater walls; hence the evidence of catastophic flooding -- the result of volcanism melting huge pockets of ice. And I am going to add my own wrinkle (probably not original): that the differentiation of Mars into a rougher southern hemisphere and smoother northern hemsphere represents something like Earth's Pangea stage, ie, the northern hemisphere is a vast frozen sea covered with a thin layer of ice.

[Juramike]

Well....looking at the morphology of the channel networks, it appears that the channel networks were not formed by rainfall, but rather from subsurface reservoirs.

Check out:
Gulick, V.C. Geomorphology 37 (2001) 241-268. "Origin of the valley networks on Mars: a hydrological perspective." (pay for article, link here)

Fully freely accessible articles (confess I haven't read these yet):
http://www2.ess.ucla.edu/~nimmo/ess250/baker.pdf

Carr and Head, GEOPHYSICAL RESEARCH LETTERS, VOL. 30 (2003) , NO. 24, 2245. "Basal melting of snow on early Mars: A possible origin of some valley networks". doi:10.1029/2003GL018575
(accessible here)


The Gulick (and others) articles give very good evidence that the valley networks were formed from subsurface sources (amphitheatre-headed valleys, very low drainage densities, low-Strahler order networks with high bifurcation ratios, etc.).

The valley networks are also very localized. One example in the Gulick article was of a dense valley system in Warrego Valles that was situated along a topographic break - yet neighboring areas also on the topographic break (same geology, same climate) were totally devoid of channels.

Their hypothesis is that Mars was covered in snowfall and melted in a few places due to magmatic activity and released water catastrophically. Other regions of snowfall that didn't melt quickly simply sublimed away slowly.