Residual and Eluvial Deposits and Drift Mining

[MrGneissGuy]

Hey guys I've been prospecting the San Gabriel wilderness for a while now, specifically the east fork, and I have so many ideas or thoughts and nobody to talk to about them. So, I hope y'all don't mind me tossing around ideas here . Often times I find myself rambling on tangents, so I apologize if I do that, I have terrible ADD.


So for a lot of you that aren't familiar with the area, the San Gabriel mountains are surprisingly steep and difficult to traverse. I wanted to point this out from the start because a lot of good looking spots might be really difficult to climb to...these are honestly some of the spots I'm most interested though. Anyways I digress...


Based on my extensive historical research, some of the best gold in the area is coming from drift mines and bench deposits. Because of this, I have discovered the terms "residual deposits" and "eluvial deposits" and now I'm fascinated with them. I've basically been prospecting using historical maps and google maps for drift mine areas without really realizing it, so I think I'd like to focus my efforts more toward these kinds of deposits. Maybe that's a bad idea as far as profitability goes, but luckily I don't prospect to make a living, I just like finding cool stuff?

However, I feel like I have no idea what I'm looking for still besides like cobblestones high up on a hillside representing a bench deposit. How is that different from a drift mine really?

This photo is an example of a drift mine found in the area, but I have no idea why it is where it is. I'm thoroughly confused... What are the clues to look for to open up a new drift mine? What about good clues for residual and eluvial deposits? It almost seems like I could just comb the hillsides with a metal detector and eventually I'd find something of interest. Thoughts?

 

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[IMAUDIGGER]

Yes in certain areas, you can comb the hillsides and find things of interest. Especially if you research and map fault lines in relation to past mining activity. Many times these fault lines will cross at saddles on the tops of ridges.
I always look downhill of these crossings, as well as where they cross drainages.

Many times I feel drift mines or coyote holes in eluvial deposits are simply places where the miners are chasing gold deposited on bedrock, perhaps a small shallow secondary bench which has been covered by eroded material.

Beware - drift mining is probably the most dangerous method of mining. Clues I would look for...past drift mining.

 

[goldog]

Hey guys I've been prospecting the San Gabriel wilderness for a while now, specifically the east fork, and I have so many ideas or thoughts and nobody to talk to about them. So, I hope y'all don't mind me tossing around ideas here . Often times I find myself rambling on tangents, so I apologize if I do that, I have terrible ADD.


So for a lot of you that aren't familiar with the area, the San Gabriel mountains are surprisingly steep and difficult to traverse. I wanted to point this out from the start because a lot of good looking spots might be really difficult to climb to...these are honestly some of the spots I'm most interested though. Anyways I digress...


Based on my extensive historical research, some of the best gold in the area is coming from drift mines and bench deposits. Because of this, I have discovered the terms "residual deposits" and "eluvial deposits" and now I'm fascinated with them. I've basically been prospecting using historical maps and google maps for drift mine areas without really realizing it, so I think I'd like to focus my efforts more toward these kinds of deposits. Maybe that's a bad idea as far as profitability goes, but luckily I don't prospect to make a living, I just like finding cool stuff?

However, I feel like I have no idea what I'm looking for still besides like cobblestones high up on a hillside representing a bench deposit. How is that different from a drift mine really?

This photo is an example of a drift mine found in the area, but I have no idea why it is where it is. I'm thoroughly confused... View attachment 1471898 . Thoughts?

This is the kind of hole that can get you in trouble. Loose and unstable above. Stay out.

Material wise, it looks like landslide rather than river run gravel. Maybe the gravel is below.

 

[rodoconnor]

That's a Widow maker

 

[MrGneissGuy]

Roger that guys. I'll be sure to stay away...I can't help but dream about it though.

 

[goldog]

Here's another thing to consider no matter wher you dig. You don't know the result. Over the years test holes show up. The next guy sees it and digs some more. On and on. Pretty soon there are extensive workings. There must be gold right??


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[N-Lionberger]

I know quite an epic hole like that, everyone assumes there is good gold there because there is this huge hole lol its bigger every time I look at it.

 

[Hard Prospector]

No gold is worth a man's life!

 

[Hard Prospector]

Coyote'n and playing "Russian Roulette" one in the same so far as man's mortality is concerned. Some might say; "No big deal whatever, its worth the risk!" OK tough guy fill up a 5 gal. bucket of dirt, place it on your chest and try breathing for 10 minutes.

 

[IMAUDIGGER]

Here's another thing to consider no matter wher you dig. You don't know the result. Over the years test holes show up. The next guy sees it and digs some more. On and on. Pretty soon there are extensive workings. There must be gold right??


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I have more confidence in the earliest diggings.
Around here at least...at that time there was plenty of easy gold to go around.
Due to the lack of water in some areas, mining was very seasonal and because of that, the miners had to be flexible.

They would work the high ground in the winter/spring when the small draws were running water.
Then they would switch to farming/gardening or wing dam mining along the rivers when the flows were low.

They may have been finding good gold in that drift tunnel, but found farming to be easier/safer or more profitable work.
They may have just up and left for the next big gold rush.

I have gone into drift tunnels (semi-cemented conglomerate) and found gold, but just looking at the one in the picture - I'd stay away.

When I see extensive workings, I never assume it is just a bunch of barren test holes. Someone was getting enough gold to keep them going.