Re: [meteorite-list] A question about Antarctica vs Alaska meteorite hunting.
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 [EMAIL PROTECTED] wrote: From: Ruben Garcia [EMAIL PROTECTED] Subject: Re: [meteorite-list] A question about Antarctica vs Alaska meteorite hunting. To: meteorite-list@meteoritecentral.com, Mr EMan [EMAIL PROTECTED] 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=meteorfrightp=v --- On Thu, 7/24/08, Mr EMan [EMAIL PROTECTED] wrote: From: Mr EMan [EMAIL PROTECTED] Subject: Re: [meteorite-list] A question about Antarctica vs Alaska meteorite hunting. To: meteorite-list@meteoritecentral.com, [EMAIL PROTECTED] 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 [EMAIL PROTECTED] 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 catchmeteorites? __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] A question about Antarctica vs Alaska meteorite hunting.
Hi all, As most of you know I've been a professional meteorite hunter for years. However, my expertise is limited to the southwestern part of the United States. 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? I may be planning a trip there and would like any advice on the subject. Ruben Garcia Phoenix, Arizona http://www.mr-meteorite.com http://www.youtube.com/profile_videos?user=meteorfrightp=v __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] A question about Antarctica vs Alaska meteorite hunting.
Great information, Thanks! Ruben Garcia Phoenix, Arizona http://www.mr-meteorite.com http://www.youtube.com/profile_videos?user=meteorfrightp=v --- On Thu, 7/24/08, Mr EMan [EMAIL PROTECTED] wrote: From: Mr EMan [EMAIL PROTECTED] Subject: Re: [meteorite-list] A question about Antarctica vs Alaska meteorite hunting. To: meteorite-list@meteoritecentral.com, [EMAIL PROTECTED] 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 [EMAIL PROTECTED] 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 catchmeteorites? __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
