Re: Mesozoic snow?

[Phil Bigelow <bigelowp@juno.com>]

On Sat, 11 Jun 2005 22:57:46 -0600 Swift Claw
<missraptor@deadraccoon.com> writes:
> on 6/11/05 9:57 AM, Phil Bigelow at bigelowp@juno.com wrote:
>  
> 
> > But freeze-thaw cycles CAN be
> > preserved in modern environments, and the discovery of polygonal 
> soil in
> > a Mesozoic formation would/will be an important find.  AFAIK, such 
> a
> > discovery hasn't yet been made.
> > 
> > The best place to look for polygonal paleosols in Mesozoic rocks 
> would be
> > in Australia, northern Canada, northern Siberia, and Alaska 
> (duh).
> 
> 
> But the time I see something like that happen is mainly in the 
> summer when
> the rains hit the dry soil and then dry again quickly...
> 
> ~Tiffany Miller 


Dessication cracks in mud are distinguishable from polygonal soil that
was shaped by freeze-thaw cycles.  Coarser-grained sediment is one
characteristic of polygonal soil.  Greater size and greater vertical
relief are other characters.

Ancient polygonal soil on Mars has been imaged by spacecraft from orbit.

<pb>
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