Glacier Prospecting

[sjmpainter]

Hey Steve, Looking for some advice or thoughts on Glacier detecting around south central Alaska. I picked up a GPX 5000 last year and plan to use that. My thought is to check the Glaciers in Prince William Sound during he fishing season. But I am still trying to firm up a plan. I have not found much on this subject, and would appreciate any info. Thanks.

 

[steve herschbach]

Nothing much to say. Gold in the region is small, and detecting glacial material is pure crapshoot. Gold can literally be anywhere. It is something I have studied a lot. Really the only thing you can do is bone up on glacial geology and go for it. It would be smart to keep expectations low to help waylay disappointment.

 

[sjmpainter]

Interesting, I would think with the Glaciers receding, new ground would open and make for good hunting. Last year I went to Matanuska Glacier. The results were as you stated poor. no gold but I did find a copper nugget that I am personally excited about. And lot of coins, even one from Romania.
I am new to prospecting with a detector and the GPX is a really complex unit to start with so my endeavors are primarily to learn the unit. The hope is to gain experience and head north looking for big gold. So my expectations are always high but I am realistic.
Thanks.

 

[steve herschbach]

The problem with glaciers is they are natures bulldozers. They push everything around and mix it up. What you want is settling action over time concentrating gold, not a giant bulldozer mixing it up. There are streams running in, around, and under glaciers, but geologically speaking they are extremely young and so little concentration has occurred. A rough rule of thumb is that the more recently an area has been glaciated, the less productive the placers are. Interior Alaska escaped recent glaciation and so the terrain is old. You want lots of low rolling hills, not sharp mountain peaks. So by comparison to interior Alaska southcentral in placer poor. Not that the gold is not there, the glaciers just messed it all up and there has been little erosion since. Again, geologically speaking.

But as I said, that means also that you can find a nugget just about anywhere. The bad thing being it can just be a random find. The best chance is to learn the signs for running water in glacial terrain and look for them. Do you know what an esker is? If not, you have not done enough research.

 

[Roscue2]

I agree with Steve, glaciers are basically unstoppable and move material all over the place. You might have luck if you could find a glacier's moraine (believe that is the correct term), which is where the glacier stops advancing down the mt. However, like Steve said, the material will be very mixed, so who knows where and how large the gold you find will be, if any. HH and GL

 

[sjmpainter]

esker, also spelled eskar, or eschar, a long, narrow, winding ridge composed of stratified sand and gravel deposited by a subglacial or englacial meltwater stream. Eskers may range from 16 to 160 feet (5 to 50 m) in height, from 160 to 1,600 feet (500 m) in width, and a few hundred feet to tens of miles in length. They may occur unbroken or as detached segments. The sediment is sorted according to grain size, and cross-laminations that show only one flow direction commonly occur. Thus eskers are considered to be channel deposits (left by streams that flowed through tunnels in and below the ice) that were let down onto the ground surface as the glacier retreated. Esker formation presumably takes place after a glacier stagnates, because movement of the ice would likely spread the material and produce ground moraine. Notable areas of eskers are found in Maine, U.S.; Canada; Ireland; and Sweden. Because of ease of access, esker deposits often are quarried for their sand and gravel for construction purposes.

I believe I have a rudimentary understanding of an esker. It makes sense that would be the most productive place to prospect. As no gold should be on the surface of a glacier, being that is comprised of annual snow fall and not in contact with gold bearing material.
Maybe I have not thought the aspect of concentration properly. I am assuming that the bulldozer action would be great for detecting, thinking that would leave gold close to the surface and in range of the detector. Basically the same as knocking down a tailing pile and go over it to find new exposed gold. Seems to me dredging would suffer but detecting would benefit.