Re: Mesozoic snow?

[Phil Bigelow <bigelowp@juno.com>]

On Sat, 11 Jun 2005 16:51:15 +0100 Michael Lovejoy
<michael@palaeoproductions.fsnet.co.uk> writes:
> Just a quick question - would dinosaurs have seen snow?

The dinosaurs that flew over the Mesozoic mountain ranges would have seen
a lot of seasonal snow.  Polar non-avians probably got snowed on during
the winters.  Lowland mid-paleolatitude non-avians probably only saw snow
on rare occassions.  Equatorial nonavians, almost never.

> Are there any formations that are more likely than others to have 
> had
> snowfall?

Mesozoic intermontane basin deposits (grabens) probably received more
snowfall than did the typical upper floodplain deposits and the lower
floodplain deposits that contain most dinosaur deposits.  Intermontane
deposits are generally uncommon in the geologic record (however, see the
Cenozoic of Nevada).

The problem (with your specific question) is that the effects of snowfall
don't get preserved in rock formations.  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).

Which is probably a study that only a geologist would fully
appreciate.......(ducking and running).

<pb>
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