[X] My Assistant

[Guest_AlexBlackwell_*]

The MARSIS team has a paper by Watters et al. that is being published in the December 14, 2006, issue of Nature. See the Editor's Summary for a synopsis and links.

See also "Geologists finding a different Mars underneath."

[edstrick]

"...However I don't think that is is sufficient to completely smooth the lowlands..."

I totally agree. Whether there were ever shallow seas in the northern plains, I think the area has been a persistant site of ice and dust and sand accumulation, to the depths of hundreds of meters. Flooding events that carved great outflow channels may well have dumped vast sheets of mud-water onto the plains, which promptly foze as quick-mud-ice, then has slowly "churned" over deep geologic time that is totally beyond the time scale of terrestrial periglacial processes. I strongly suspect the big boulders MRO is seeing on the plains as it searches for a Phoenix landing site have been "plucked" from more solid rocky terrain under the ice-mud and brought to the surface. We DO NOT understand this terrain if we think of it in lunar regolith or terrestrial polar processes terms and timescales, as two extreme model end-members.