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

[Rob McCafferty]

I highly recommend the book "Meteorites, Ice, and Antarctica - A personal account" by William A. Cassidy.

It goes into all sorts of technical stuff and the whole history and difficulty of the operations but is also a corking good read.

My personal favourite anecdote involves 2 grad students and the punchline "Who is it?".
Anyone whom has read the book will likely already be deep belly chuckling to themselves. 
Rob McC

--- On Fri, 7/25/08, Ruben Garcia <meteoritemall at yahoo.com> wrote:


> From: Ruben Garcia <meteoritemall at yahoo.com>

> Subject: Re: [meteorite-list] A question about Antarctica vs Alaska meteorite hunting.

> To: meteorite-list at meteoritecentral.com, "Mr EMan" <mstreman53 at yahoo.com>

> Date: Friday, July 25, 2008, 1:53 AM

> 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?

> 

> 

>       

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