[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?