Meridiani Ice theory, New theory for the formation of the Meridiani bedrock |
Meridiani Ice theory, New theory for the formation of the Meridiani bedrock |
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![]() Member ![]() ![]() ![]() Group: Members Posts: 276 Joined: 11-December 07 From: Dar es Salaam, Tanzania Member No.: 3978 ![]() |
Hi all, long time no see.
Yet another theory to explain the origin for the bedrock encountered by Opportunity. I first heard of this new theory from Universe Today; http://www.universetoday.com/2009/02/16/ne...t-mars-equator/ An abstract is available at http://www.nature.com/ngeo/journal/vaop/nc...bs/ngeo438.html The theory is interesting, but I would really be interested to know how it explains the spherules seen by Opportunity not to mention the vugs. Thoughts any one? -------------------- |
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![]() Member ![]() ![]() ![]() Group: Members Posts: 646 Joined: 23-December 05 From: Forest of Dean Member No.: 617 ![]() |
ngunn, could you elaborate on what a "closed isobar" means in this context? I'm having some difficulty picturing the topology of a blister of liquid beneath an ice-sheet. I wonder if this model has any implications for the expected local or regional topology of resulting deposits on the surface today - might the outlines of this area be evidenced in remaining terrain? The article mentions Antarctic examples of this phenomena but if I submit to the call of the Google, I'll never get this pile of work done...
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Viva software libre! |
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#3
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 ![]() |
"closed isobar" Under the ice water flows from higher to lower pressure locations. Elevation is only one of the parameters affecting the pressure, and not necessarily the dominant one. So 'lakes' don't have open surfaces but rather roofs which are in general not flat. They are places where the pressure gradient is inward along the whole circumference - hence closed isobar. Water can flow uphill as well as down, depending on the overburden in different places. I only know what I've read in popular sources but it all sounds horrendously complex - and confusing. I raised this because I think that on Mars subglacial waters could have gone on doing their work long after surface waters (or even near-surface waters) ceased to be viable. All you need is a large persistent ice layer protected by a thin crust of sublimation residue. Large buried ice deposits outside the polar regions have indeed been discovered in recent years, so some of the ice is still there. It may now be frozen right down to its base (I don't know) but it need not always have been, and there could once have been a lot more of it. Normally I keep quiet on this, but whan someone proposes massive equatorial ice deposits on Mars I think of Antarctica. |
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