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That's a pretty good writeup with some nice diagrams. 

Usually people only talk about paleo placers in reference to California. One of my personal major pushes in the placer gold realm today is to locate these old channels in other states where they've been overlooked or ignored/unrecognized. I've found them in every state I prospect in. It's not just limited to gold though, I've found placer jade in Wyoming by concentrating on looking for older gravels from long extinct rivers. Sometimes the gravels themselves are mostly eroded away and difficult to locate, but there are still residual deposits of garnets or other heavies. In Colorado I found a bunch of heavy zircon sand which I used to trace an old channel. A pan can show the presence of minerals which could have only gotten to where they are at by stream transport at one time. In the case of the zircons, I was able to trace the formation which they originated from and thus was also able to find more parts of the long extinct and mostly invisible channel many thousands of feet elevation above and many miles distant. Things like this can be employed absent large visible paleo gravel deposits.

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I once met a guy who owned a book store in Elko, Nevada.  He told me that as a general rule all the ancient channels had run towards the west from the rocky mountains long before the Sierras.  At the time I didn't know what he was talking about.

They used this and of course a lot more information to discover gold in the Carlin Trend and some quite large nugget patches up that way.

I guess now when you find ancient river gold high in the Sierras he knew what he was talking about.

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1 hour ago, oneguy said:

Stumbled onto this interesting article form another site......  Not sure where to post this but Steve can relocate it where he see's fit?

Thanks for sending, great article and videos. Tertiary channels are plentiful here in the Sierra's. The problem is that some are rather deep with hundreds of feet of alluvial gravel covering the heavies. The trick when metal detecting is to find shallow channels. But those have practically all been mined already. 

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More on California paleo channels...

  • The Tertiary Gravels of the Sierra Nevada of California 1911 USGS Professional Paper 73 by Waldemar Lindgren. A California geology classic. An account of the Tertiary formations of the Sierra Nevada Mountains and the origin and distribution of the gold-bearing (auriferous) gravels.
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25 minutes ago, Steve Herschbach said:

More on California paleo channels...

  • The Tertiary Gravels of the Sierra Nevada of California 1911 USGS Professional Paper 73 by Waldemar Lindgren. A California geology classic. An account of the Tertiary formations of the Sierra Nevada Mountains and the origin and distribution of the gold-bearing (auriferous) gravels.

Thanks, Steve. I was about to post the exact same document but thought people might not like it because of how old it is. However, it is a great read and a lot to learn in it. I am glad you posted it.

This one is also good, it shows all tert. channels and deposits (Clark, 1965-see attached pdf)TertiaryChannels Sierra Nevada.pdf

 

 

 

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The extremely detailed 1961 Deb Chandra Special Report 67 is also a great resource for the American River tertiary gravels.

http://www.mylandmatters.org/Library/Item=172

In 2012 we managed to borrow one of the three remaining copies of the very large hand colored tertiary gravels map in the original 1890 Colfax Folio from the Federal Repository. We did digitize that map as well as the Lindgren, Clark, Olaf Jenkins and Deb Chandra reports to create the interactive geology mapping on the North and Middle Fork FootPrints.

 

 

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This is a GIS based map of the "hydraulic mine pits of california" - has many unnamed small occurrences: Some you probably never knew was there.

https://www.sciencebase.gov/catalog/item/571976c2e4b071321fe22947

You can use different base maps.

When I left the USGS in 1995 I was at the time working with Warren Yeend on expanding the Tertiary Gravel study beyond Nevada County. One of the big unanswered questions is the primary source of the gold in the Tertiary Gravels? There have been proposals that there was a similar suture system to the current Mother Lode to the east that has been too deeply eroded: Garside at UNR (and others - some Aussies I can't remember) have proposed a possible source east of the current Sierra Nevada. For the Yuba/Feather area was it simply very rich pocket type occurrences like the 16:1? Lots of other proposed explanations.

Rich Goldfarb and Erin Marsh at the USGS in Denver took over much of this work, bringing in several grad students to work in the Mother Lode, but unfortunately the USGS lost its focus and any significant ore deposit research has long gone by the wayside.

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38 minutes ago, GeoBill said:

This is a GIS based map of the "hydraulic mine pits of california" - has many unnamed small occurrences: Some you probably never knew was there.

https://www.sciencebase.gov/catalog/item/571976c2e4b071321fe22947

You can use different base maps.

When I left the USGS in 1995 I was at the time working with Warren Yeend on expanding the Tertiary Gravel study beyond Nevada County. One of the big unanswered questions is the primary source of the gold in the Tertiary Gravels? There have been proposals that there was a similar suture system to the current Mother Lode to the east that has been too deeply eroded: Garside at UNR (and others - some Aussies I can't remember) have proposed a possible source east of the current Sierra Nevada. For the Yuba/Feather area was it simply very rich pocket type occurrences like the 16:1? Lots of other proposed explanations.

Rich Goldfarb and Erin Marsh at the USGS in Denver took over much of this work, bringing in several grad students to work in the Mother Lode, but unfortunately the USGS lost its focus and any significant ore deposit research has long gone by the wayside.

Awesome, thanks GeoBill! I have downloaded the kml file, works great with Google Earth. Now, if we would just have a modern good PI detector that could discriminate. The amount of trash I usually collect in hydraulic pits is mind-boggling. These areas are prime territories for the GM or Nox 8. SDC/Zed completely useless. 

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