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Ancient River Channels


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On 3/6/2021 at 2:16 PM, oneguy said:

In my limited experience and areas, I find hydraulic areas have less trash than the river bottoms where the dredges operated....

If you are talking about recreational dredges, I dredged for many years on most of the mother lode rivers and the trash you talk about, was rarely evident. Honest. And that was for six full summers of dredging.
If you meant the huge dredges that tore up miles of river bottom, that's a different story I guess.

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1 hour ago, flakmagnet said:

If you are talking about recreational dredges, I dredged for many years on most of the mother lode rivers and the trash you talk about, was rarely evident. Honest. And that was for six full summers of dredging.
If you meant the huge dredges that tore up miles of river bottom, that's a different story I guess.

Thanks for following up Dave. I thought he meant the bucket lines. I once was at the South Yuba and indeed the metal trash was mind blowing. But good to know that the regular dredge fields appear less trashy. I need to find the dried out ones then 😁

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On 3/7/2021 at 9:17 PM, flakmagnet said:

If you are talking about recreational dredges, I dredged for many years on most of the mother lode rivers and the trash you talk about, was rarely evident. Honest. And that was for six full summers of dredging.
If you meant the huge dredges that tore up miles of river bottom, that's a different story I guess.

I was referring to big bucket line dredges.......

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Great resources and knowledge being shared.  Thanks for opening up more opportunities and potentials.  Now I just need the GPX-6000 and off I go.

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  • 8 months later...

Recent discovery of fossils along the lower Mokelumne River by East Bay Municipal Utility District (CSU Chico) was followed up by Cathy Busby, Geologist, UC Davis who moves the topic of Ancient River Deposits further east to the Tertiary Miocene composite volcanos located along the summit of the Sierras. Other studies combine to move the source of the Tertiary Eocene rivers further east into eastern Nevada. My understanding is that rhyolite ash from the eastern Nevada calderas’ multiple eruptions were layered first in these ancient river valleys. The rivers continued to cut through the rhyolite tuff deposits in the river valleys. The eastern Nevada volcanic arcs migrated westward as the subduction plate dip angle steepened depositing more rhyolite ash/tuff in the ancient river valleys. The ancient rivers continued to cut new channels through the tuff at higher elevations. An ancient range of mountains located in eastern Nevada provided the water and sediments for these Eocene rivers as they flowed western across a plateau then down a west dipping slope into the Ione Sea or Pacific Ocean. With the extension of the plateau into the basin range and the uplift of the Sierras the younger western Miocene composite volcanic deposited both rhyolite, andesite and on occasionally basalt on top of the Eocene deposits. The final capping deposit being from mud flows (similar to St. Helens). The current thinking is that the gold hydraulic from these Eocene river beds at lower elevation was captured as the rivers cut through the lode veins located of the western Sierra foothills. Placer gold along with white quartz pebbles were found on the original ancient river beds on bedrock.  My question is was some of that gold picked up and carried along with erosion sediments from that ancient eastern Nevada mountain range and from the fault zone located in the eastern Sierra? I have been finding rounded white quartz pebbles at the base of the spring up here at the shack. The ridge above fits the sequence of volcanic deposits. Found six more springs and seeps on the other side of the ridge. Bedrock is a 100 feet down and the tuff deposits are 400 feet up. Glacier erratic on this side of the ridge suggest the quartz pebbles may have arrived here by ice flows. I am still scouting with the detectors but a 800 foot drift may be required to answer the question. Any thoughts?
 

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On 3/7/2021 at 8:10 PM, Swegin said:

Does the name Stan Grist ring a bell with anyone?   I don't know if he was legit or not but he a gold coarse if I remember right.  He had maps showing  Ancient River channels from Canada to somewhere in South America.

 

 

 

http://www.onelight.com/hec/targets/Alaska/Stan Grist's resources for treasure hunting, gold prospecting, metal detecting and exploration. .htm

 

This guy I think

 

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