[meteorite-list] A question about Antarctica vs Alaska meteorite hunting.

[Ruben Garcia]

Great information, Thanks!

Ruben Garcia
Phoenix, Arizona
http://www.mr-meteorite.com
http://www.youtube.com/profile_videos?user=meteorfright&p=v


--- On Thu, 7/24/08, Mr EMan <mstreman53 at yahoo.com> wrote:

> From: Mr EMan <mstreman53 at yahoo.com>
> Subject: Re: [meteorite-list] A question about Antarctica vs Alaska meteorite hunting.
> To: meteorite-list at meteoritecentral.com, meteoritemall at yahoo.com
> Date: Thursday, July 24, 2008, 4:24 PM
> Hello Ruben  Good question.
> 
> What makes the recovery in Antarctica is a combination of
> rare processes and not just glaciers catching up
> meteorites.   It takes a rare combination of bedrock, ice
> and wind to expose the meteorite fields in Antarctica.
> 
> Meteorites falling into the main flow are likely lost
> forever.  But if it falls along the edge of the field in a
> side lobe-- not in the main glacial flow--there is a chance
> it can be exposed again.  Sometimes thousands of years
> later.  The ice in the top portion of the lobe doesn't
> scour the bedrock and stir up rock fragments like the main
> flow does and has minimal inclusions of earth rock in the
> load carried by the ice.   A lobe occurs near a bottleneck
> and is like a slow motion wave getting sloshed out of a bath
> tub-- being pushed out of the "tub" itself by the
> main flow and rising bedrock.  When the lobe hits the
> valley rim-- a gentle slope or buried ridge-line, the ice
> is forced  up and over it, exposing the ice to very high
> velocity and extremely dry winds. This action scours away
> the ice matrix --perhaps even sublimates some ice directly
> into water vapor.  In any event, the ice is removed by
> wind action leaving the meteorites concentrated on
>  the surface.  "Concentrated" implies a placer
> deposit but in fact means that in fives and tens meteorites
> are exposed each season before the ice flows over the slope
> and they are reburied in ice unless recovered by the annual
> meteorite search teams.
> 
> I believe that a few iron meteorites have been recovered in
> glacial moraines elsewhere but that is a different
> concentration mechanism and they certainly aren't
> separated out from the earth rock!.  Active glaciers such
> as associated with caving icebergs carry whatever load they
> have inside them into the sea.
> 
> Meteorites don't seem to survive long in moist frequent
> freeze thaw environments making finding stone meteorites
> remote.  I don't know the circumstances of recent
> Canadian meteorites and couldn't say if they were
> related to glaciers.  The environment in glacial fields is
> against stones but favors irons, IMHO, so long as the ice
> doesn't make icebergs but ends in annual moraine
> building piles of debris.
> 
> Elton
> 
> --- On Thu, 7/24/08, Ruben Garcia
> <meteoritemall at yahoo.com> wrote:
> Hi all,
> I know that many of you follow the work done in Antarctica
> a lot more closely
> than I do. I know that meteorites have been recovered there
> for over two
> decades and more recently in eastern Manitoba, Canada. All
> due to ancient
> glaciers and their movements. My questions are as follows: 
> 
> 1)Has anyone really searched for meteorites in other
> glacial areas such as
> Alaska? 
> 
> 2)Is there any reason to believe that meteorites
> wouldn't be found there?
> 3)Are the Alaskan glaciers old enough to sufficiently
> "catch"meteorites?