Sunday, October 30, 2011

Periglaciologist Barbie? ... no, Fred!

I couldn’t do it, couldn’t bring myself to buy a Barbie doll.  When I was a kid Barbie made her debut and both of the other girls on the street had Barbies.  I had no Barbie doll -- what I wanted more than anything was a baseball mitt.  But not wanting to be left out of Accretionary Wedge #39, I present to you ... (fanfare)

... Fred the Periglaciologist!  Living where he does, his is a profession of choice.

Periglacial sand wedge, southeast Wyoming.
The source of the spectacularly-colored fill
awaits elucidation.

Fred is in his eureka pose, having just come across a spectacular exposure of sand wedges in a ditch in the west part of town.  “Sand wedge” is a misnomer; fill material is not restricted to sand -- it can be finer or coarser.  The name is used to differentiate these wedges from ice wedges, which form in wet environments.  These that Fred found are relics of cold dry Pleistocene times when there was permafrost in the Wyoming basins.  Thermal-contraction cracks filled up with whatever blew in -- loess, sand, miscellaneous debris.

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