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wjbell

Metal detecting old dredge tailing piles

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Actually they have done quite a bit of dredging here in AZ. Here is a link to some of what they did in the 30's.

http://scotp-cp.iii.com/iii/cpro/DigitalItemViewPage.external?lang=eng&sp=1002343&sp=T&suite=def

Now I have some other links if anyone is interested. My understanding on some of the dredging is that it didnt go well back in the day. Weather patterns and all, they lost some rigs on the big river to flooding.

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Ah please let me add, that I have also acquired a list of ponds and lakes that have been dredged. From the people I talked to, it depended on the location of the pond or lake as to whether they had to haul off thier tailings or not. Recently the Pena Blanca lake was drained because of the Mercury content. It offered up some interesting items...but thats another story.

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Bill.

Most river dredges were "Spud" barges. In case you don't know a spud barge usualy has 6 spuds that are pileings, some time wood with steel reinforcement, sometimes all steel, round or square. They are raised and lowered by winches. They are located on the 4 corners and in the center of the bow and stern.

Generaly they have anchor winches on all four corners, must of them discharged the tails directly back to the water callled the "pond" which they dug and moved with them keeping the water from running away so they could go up hill with the stream gradient. They had a conveyor out the stern which in some cases was fixed and in others was movable up and down and side ways, some on the biggest rivers discharged into barges.

To dredge they would carry out anchors or cables to trees ahead of them on each side. they would drop the rear center spud and raise all the others, lowering the cutter head they would pivot on the spud using the winches to pull right and left and raising the spud move ahead. The semi-circular pattern of the piles repesents this swinging motion, diving some of these dredge ponds reveled to me that a change in material discharged in a particuler pile would signal a change in the bottom structure, I found ( by diving with my Hookla) that there was huge house sized boulders and bedrock outcrops that they went around or over ( Sorry, I will get some flack from certain dredgers in a certain state who beleives this is their closely guarded secret!). These spots are excellent spots to dredge with todays small dredges, they can be a bonaza if you are the first guy since 18XX to dredge around them!

Smaller dredges (wood) where dismandeled and the machinery used again,some of them rotted or burned where they stopped the last time ( speaking of the 1800's era). Good examples are at Idaho City, Fetherville and some other spots in Idaho, from Idaho City to Grimes Pass there are 27 miles of dredge piles along the Grimes and other creek drainages ( some 2 miles wide) and this is not the biggest! When the creeks got to narrow and steep for a floating dredge they would use a "Monitor" a huge nozzle to wash the creek and hilside down into a sluice.

They did not just dredge the existing stream beds but went from wall to wall, mountain to mountain as long as they where getting gold and they still didn't get it all! I have heard that everytime you move gold bearing material you loose 10% of the gold, I beleive it ! I found a gram nugget behind the baseboards when i was replacing the floor in my motor home, I know it was mine because I put that floor in too!.

Good Luck

Max

BTW: The Folsom and other CA river dredges where huge compared to most dredges of the times.

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A better example are these piles very far from the river

Dredge Piles

Those tailings are actually very close to the river and in reality they are a gravel bar in the river channel. Most likely from one of the old Yuba Dredges that proliferated in the area. I do believe the last one was still in operation until the early 60's

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Ok thanks guys. It seemed by the patterns of the piles that it would have had to be stacked right off the back of the working dredge. I was always trying to figure out if they were dredging the river, how come the piles are sometimes a half mile away. I read somewhere too that they created a pond where they were working and moved it with them. I guess this is the case here.

But they did dredge the river too, so does that mean there are piles like these at the bottom of the river wherever they dredged?

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Not sure this will help but here it is. I went to high school in Folsom in the early fifties. One day my dad took my brother and I out to a flat treeless area west of highway 50 several miles from the river and in the middle of this was a working dredge setting in a pond of water. The dredge was about 200 ft. long and a 100 ft. wide, The workman took us on a tour of the dredge and showed us some of the gold that they got, very interesting. Behind the dredge were acres and acres of tailings, this was only one dredge there were others working in the area. I'm sure if you go out west of highway 50 from Folsom you may see these rows and rows of rock left by the dredges. At that time there were several ponds in Folsom area where they stopped dredging and removed the dredge. My 2 cents worth. John

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Not sure this will help but here it is. I went to high school in Folsom in the early fifties. One day my dad took my brother and I out to a flat treeless area west of highway 50 several miles from the river and in the middle of this was a working dredge setting in a pond of water. The dredge was about 200 ft. long and a 100 ft. wide, The workman took us on a tour of the dredge and showed us some of the gold that they got, very interesting. Behind the dredge were acres and acres of tailings, this was only one dredge there were others working in the area. I'm sure if you go out west of highway 50 from Folsom you may see these rows and rows of rock left by the dredges. At that time there were several ponds in Folsom area where they stopped dredging and removed the dredge. My 2 cents worth. John

Yeah, that's interesting. Maybe around this area? It's south of 50 but just massive amounts of tailings.

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Guest bedrock bob

Ok thanks guys. It seemed by the patterns of the piles that it would have had to be stacked right off the back of the working dredge. I was always trying to figure out if they were dredging the river, how come the piles are sometimes a half mile away. I read somewhere too that they created a pond where they were working and moved it with them. I guess this is the case here.

But they did dredge the river too, so does that mean there are piles like these at the bottom of the river wherever they dredged?

Yup, or there usted to be. Floods and high water have reworked a lot of the tailings in the stream course.

Even in the desert, where wells were dug all along a water course and pumped into a "pond" that moved with the operation, the piles in the middle of the water couse have been flattened out and carried away by floods. This type of operation was limited to the areas that had the groundwater to supply the dredge and had the soil consistency to hold water long enough to dredge.

Sometimes the piles in the desert LOOK like dredge piles, but they were actualy dragged out from the stream course with big draglines and scrapers and run through a mobile wash plant. The results look a lot like "dredge" tailings but were not done by a dredge. In most of these areas the coarse material was seperated from the fine material, and so there will be two different piles of aggregate size rather than piles of material seemingly unscreened.

That is where knowing just how they did the operation comes in handy. Lots of different methods to classify and carry the "slack" material away from a machine. If the screened cobbles (header) was carried away with the tailings then it shoudl have al the large gold still in the gravel. If the pile is just "tailings" then you will be very dissappointed in the gold recovery...It has already been processed and MOST of the gold has been recovered.

Bedrock Bob

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Yup, those are some of the tailings from the old bucket line dredges. That area East of Sunrise Blvd is private property and fenced off...... All of the dredge fields around Folsom are in /on the old American River bedrock

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That is where knowing just how they did the operation comes in handy. Lots of different methods to classify and carry the "slack" material away from a machine. If the screened cobbles (header) was carried away with the tailings then it shoudl have al the large gold still in the gravel. If the pile is just "tailings" then you will be very dissappointed in the gold recovery...It has already been processed and MOST of the gold has been recovered.

Bedrock Bob

How can you tell if the tailing piles have the screened cobbles in them or just tailings? Do you know if the two areas around folsom in the satellite views would have been just tailings, or the header stuff too?

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Guest bedrock bob

How can you tell if the tailing piles have the screened cobbles in them or just tailings? Do you know if the two areas around folsom in the satellite views would have been just tailings, or the header stuff too?

If the piles contain big rocks, the header and tails were carried away together...I believe this was the usual way a river dredge did it but I do not have wide experience at that. If the piles are fine stuff, and other piles aare coarse rock, I would concentrate on teh coarse rock...nuggets weer screened off and were carried away.

Now, in my country the piles re usually screened. Some are coarse and some are fine. The fine piles usuall yhave only the occasional piece of detectable gold, but the coarse piles have nuggets as big as your thumb that were screened off.

That does not mean that all piles are the same everywhere. I know nothing about the area or the history that you are working in...

Bob

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If the piles contain big rocks, the header and tails were carried away together...I believe this was the usual way a river dredge did it but I do not have wide experience at that. If the piles are fine stuff, and other piles aare coarse rock, I would concentrate on teh coarse rock...nuggets weer screened off and were carried away.

Now, in my country the piles re usually screened. Some are coarse and some are fine. The fine piles usuall yhave only the occasional piece of detectable gold, but the coarse piles have nuggets as big as your thumb that were screened off.

That does not mean that all piles are the same everywhere. I know nothing about the area or the history that you are working in...

Bob

Ok, The piles here are a combination of everything. From 2 foot diameter boulders all the way down to tiny pebbles.

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Guest bedrock bob

Ok, The piles here are a combination of everything. From 2 foot diameter boulders all the way down to tiny pebbles.

Then I would have absolutely no idea which piles would be "better" than the others.

Here, the fine gradient piles have about 2 nuggets a day in them, most 1/2 penny or less. The larger piles have one nugget every couple of weeks in them, one ounce or less. That makes the big rock piles a hell of a lot more productive but tedious detecting. The big rock piles have most of the hot rocks and trash, and are really tough to dig through. I often detect the small piles even though the big piles are better just because it does not wear on my patience as much.

So nothin is easy huh?

Bob

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Then I would have absolutely no idea which piles would be "better" than the others.

Here, the fine gradient piles have about 2 nuggets a day in them, most 1/2 penny or less. The larger piles have one nugget every couple of weeks in them, one ounce or less. That makes the big rock piles a hell of a lot more productive but tedious detecting. The big rock piles have most of the hot rocks and trash, and are really tough to dig through. I often detect the small piles even though the big piles are better just because it does not wear on my patience as much.

So nothin is easy huh?

Bob

Well, here's the only thing I brought home today... a couple of pictures. Pictures don't do it justice but there are piles as far as the eye can see. They're roughly about 25 feet tall, just rows and rows of them.

tailings1.jpg

tailings2.jpg

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What's interesting is those rocks in that ancient floodplain look like they are all volcanic, or some type of greenstone. Not much quartz there. But if you travel higher into the hills we have ancient riverbeds made up entirely of just quartz. Weird stuff.

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Guest bedrock bob

Looks really familiar. Could be a photo of one of my favorite hotspots. There are about a billion rocks for every nugget. I figure that you have about a zillion rocks just in that picture. Bound to be a big hunk of gold screened off in all that yardage with our name on it. just gotta get that coil over the top of it.

I dont know a darn thing about the history of the area or how coarse the gold was, but if'n the gold was nuggety they screened off some big uns...period. In my area there was a lot of float screened off. I have found more hard rock gold than placer gold in the tailings. The only way the real shockers will be found is by a beep artist.

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There are about a billion rocks for every nugget. I figure that you have about a zillion rocks just in that picture. Bound to be a big hunk of gold screened off in all that yardage with our name on it. just gotta get that coil over the top of it.

Gee, you really know how to give a guy encouragement... :hahaha:

Anyone got a spare backhoe and trommel? ;)

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Wes... different streambeds from different time epochs!

As far as trying to recover gold from the oversize rock tails.... just imaging all the spaces in between the rocks and lets say you are trying to recover a 1 ounce sinker... move a few rocks and it will just keep getting deeper. I tried and tried to get nuggets out of those tailings and gave up. However, the places to watch are where the tails are dozed for development ! Which by now, has pretty much slowed to a trickle. The areas West of E. Bidwell St are now pretty much built out.......

Here is a small patch area for you to try..... It's called the LaTrobe area or the "Sawmill". nuggets are usually 1 gram or less. Stay South of the small dirt road that crosses over the top of the hill with the trees. That is a good road to park on. That is public property reserved for a future school.

N 38 36.483 W 121 2.803

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Hello, All i need a little help here. I am trying to find out how i join the SPMA? If anyone could help i would be thankful!

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Wes... different streambeds from different time epochs!

As far as trying to recover gold from the oversize rock tails.... just imaging all the spaces in between the rocks and lets say you are trying to recover a 1 ounce sinker... move a few rocks and it will just keep getting deeper. I tried and tried to get nuggets out of those tailings and gave up. However, the places to watch are where the tails are dozed for development ! Which by now, has pretty much slowed to a trickle. The areas West of E. Bidwell St are now pretty much built out.......

Here is a small patch area for you to try..... It's called the LaTrobe area or the "Sawmill". nuggets are usually 1 gram or less. Stay South of the small dirt road that crosses over the top of the hill with the trees. That is a good road to park on. That is public property reserved for a future school.

N 38 36.483 W 121 2.803

Thanks for the tips. Why is gold in that latrobe area, was it an old mined spot?

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There is an old saying, Gold is where you find it! The Indians said it was where the sun was crying they called nuggets tears of the Sun. Find a copy of Tertiary Deposits of the Sierra Nevada. It's old and hard to find, but will answer many of your questions. I think someone posted a link to an online copy.....

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ED HEAD,

So as not to interfere with this thread, I sent you a PM in this forum.

Greg

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I have often wondered about beeping thw tailings, but my gut tells me that not much big stuff would be down as far as sacto/ folsom area. Wouldn't areas up towards Jackson/ Ione be a better shot at finding a nugget? Like Michigan bar? Just asking.

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