By Steve Herschbach
The earth has been warming and glaciers retreating for over 15,000 years. Almost everything in the part of Alaska I lived in was recently exposed by glaciers and been prospected the last couple hundred years. Glaciers are nature's bulldozers and they destroy and mix. The gold distribution in glacial material is generally random and sparse. Where water has had time to work glacial deposits new placers can form, but the short geologic time spans we are talking about usually mean small erratic deposits. The good news is that also means you can maybe find a gold nugget just about anywhere in glacial material.
If you watch the video a second time and pay attention to the area that becomes Alaska you will see that Anchorage, on the southern coast, was buried under 3000 feet of ice not too long ago. The interesting part is northern Alaska is largely ice free. This is extremely important. The placers are much older and more extensive in Interior Alaska than in the southern coastal areas.
The northern US was heavily glaciated and much of the material was pushed down from out of the north in Canada. I find glacial terrain interesting because glaciers have melt water running under them and along the edges, which form small oddball placers in the strangest places, and other placers are possible in the large outwash areas.
I am discovering there was a lot more glacial activity in the Sierras than I would have imagined and so this is still very relevant for me prospecting in California.
These links may not be for your exact area but all contain good information about glacial geology and prospecting.
Great freebie article Gold in Kansas
And a small related article at the ICMJ Undiscovered Placer Deposits in Alaska
Really good stuff starting page 117 on Gold Placers of Colorado
Placer Deposits of the Yukon
Geology of Tertiary and Quaternary Gold-Bearing Placers in the Cariboo Region, BC
Here is some really technical stuff for those so inclined Glacial Geology & Prospecting
Glaciers of California
A much more prospector friendly version can be had in an excellent but pricey book by Chuck Lassiter, Midwest Gold Prospecting at http://www.midwestprospector.com/book.html
I have a copy in my library of the best of the best. It is a high quality book with color maps and illustrations and a no-brainer at about half the cost. For $29.95 you have to just love books as much as me as that is as much as the Chris Ralph encyclopedia and this book would be a chapter in Chris book. That said, I have never seen the particular subject of glacial region prospecting covered better and more understandably anywhere else. It would be the go to primer for anyone interested in the subject.
By Allen M
I was out this past weekend with my Gold Monster 1000. Here is a picture of a rock that I came across that had crystals and what I believe is black sand. I have come across black sand by it self and has done the same issue with my machine. Reading and sounding hot and then a blank sound as well.
1) I assume that you can find black sand like this still in a rock with Quartz.
2) Is is not true that usally when you find black sand you may end off finding gold as well because black sand and gold go together.
here are four pictures of the rock.
I nabbed a pretty neat find the other day and I think it was sunbaker...
Is it only a sunbaker if you saw it before you disturbed it or is it still a sunbaker if the rock that it's lodged in tells a sunbaker tale? Every dirt dog can tell what half of a float rock was in the ground and what half was face up.
This is a rock with a nugget lodged in it that tells one of those sunbaker tales.
Is it a sunbaker?
Was it a sunbaker?
Is it not a sunbaker?
It's wedged in there really good! I haven't tried to yank it out because it's so unique as a sort of specimen of a bedrock nugget trap. I've picked at it and got no movement, plus it survived getting tossed around in my pack on my hike.
An interesting find too! One of those days, patch hunting a new area (this new area hasn't met the three nugget threshold). All I had in my pocket was trash and my nug jug only held my test nugget. But lo, another signal! Few and far between, they are out here. Giving the spot a boot scrape moves my target. Probably surface trash, a bullet. Gotta know. These 4 rocks. These 3. These 2. That one... it's not a hot rock? Turned in hand to reveal a little smooshie stuck in a crack! WHOA!!!
My strongest theory is that this "specimen" is a remnant of the bedrock that trapped some gold, all the bedrock having been eroded away. The gold since washed down the hillside and into the main drainage, perhaps all the way into the basin... But hopefully it has only travelled just past where I stopped detecting for the day and I get a whopper bonanza another day! 😂 Yeah right.