How Important Is Getting To Bedrock?

[GB_Amateur]

First off, I'm talking about placer gold.  Secondly, I realize this is a simple question with a very complicated answer.  But in probability/statistics/percentage terms, I think it's not that crazy.

Most, if not all gold is going to end up in the ocean if it's not recovered by one of us.  But even once loose from it's origin that could take many 10's of millions of years.  In the meantime, gravity is pulling it towards the earth's center.  Even dense clay can stop it for a while, but usually it sinks until it reaches bedrock, and even then it can be horizontally displaced unless it falls in a crack/crevice.

If you're using a metal detector there is a minimum size that can be detected.  "Young gold" (that which has only reached its current location in the last days, months, or even few years) tends to be sub-threshold gold in terms of metal detecting (I think -- please correct me if I'm wrong).  So if you're going to find placer gold with a metal detector it most likely has been at or near its current location for a long time, meaning on the order of tens or hundreds of thousand of years at a minimum.  (Obviously there are exceptions, but I'm talking in general.)

So, to cut to the chase, if I'm using a metal detector to find placer gold and I'm not getting to bedrock, am I just spinning my wheels?

Postscript:  I'm no expert on this.  Maybe my assumptions and conclusions are completely bogus.  If so, I welcome/encourage you to say so.  I'm trying to learn, not protect my ego.

 

 

[fredmason]

Well, it depends...

If you are talking about detecting in a stream or river then you might need to get to bedrock, especially if there is a deep over-burden and you know there is gold in that location. I generally stay out on moving water when detecting gold because there are easier ways to get gold from a running stream.  Along the sides and terraces the gold can be deep or shallow so those can be productive. In desert areas flash floods tend to move dirt/gold in floods so it can be in various layers.

The best thing to do is detect and sample various layers...that can be a lot of work...

so, as I started, it depends on the terrain, type of gold and mode of transport and disposition of the gold.

There are others that can give you much better answers...Jim Straight, Chris Ralph and Ray Mills have written excellent gold-getting texts...

The ICMJ has many years of mining wisdom in its archives...

good hunting

fred

[Ridge Runner]

Hey GB

Bedrock is like a brick wall and that is nothing gets past either. It was said about various layers by Fred but be sure you don't stop if the layer is thicker. Why? It could be what is called false bedrock. Oh this thicker layer could hold lots of gold but it have been made by time but the true bedrock is below that. Depth unknown.

Chuck

[mn90403]

Fred was a good 'poster' for you to read some of his past posts.  His years of hunting and knowledge is greater than mine.  He references some good guys who have written.

One book and writer you should add to your list is Chris Ralph (Fred said ICMJ so you will see him there).  He has written a book 'Fists Full Of Gold' which is kind of a modern encyclopedia on the subject.

I would generally agree with your assumptions.  My departure with them would be involving plate tectonics and your assumption that all gold would make it to the ocean.  Plate tectonics is the elephant in the room.  It will push everything around including ancient rivers, ocean beds and lakes which were once at the end of the streams.  Gold on the west coast is heavily dependent upon that and the volcanic activity associated with it.

Here is a page which describes some of the specific forces that determine recoverable placer gold (with and without a metal detector).

http://www.goldrushnuggets.com/tyofgopl.html

You've opened a subject that I think the old timers knew more about than we do today.  We are just following them as Jim Straight says:  'Follow the dry washers' in the desert.  We all follow the miners elsewhere for the gold they missed and their relics.

Good prospecting to you wherever you go.

Mitchel

[Hobo]

In a mountain stream gold will migrate down until it reaches bed rock, then in a  violent  flood it scoots along the bottom until it finds a hiding place ,like a crack , a hole or some obstacle to hide behind .Imo gold does not travel far from the place It entered the stream, most of the gold that reaches the oceans which is very little is very fine and take eons

,

[rumblefish]

My (limited) experience of prospecting rivers is that it is a pain in the ass!

I'm referring to the difficulty in actually digging in water. Unless the water is slow moving, shallow and very clear, it is hard to see what and where you are digging, and the flow of water makes lifting the gravels tricky, especially when you have cleared the big stones and are digging the finer, heavier material, which is what you are looking for. It's much easier to dig (where permitted) the old, dry course of the same stream or river. It's much easier to work, you don't need waders and waterproofs, you don't get attacked by so many mosquitos and you can see what you are doing.

As you said in your post, most of the recently deposited gold that hasn't reached the bedrock is generally too small to detect with a machine. I have an SDC 2300 and it won't detect any of the gold that I find. The pieces are too tiny.

So I would tend to agree that if you want to detect in water, you are going to have to find a spot in a gold bearing river where you can access the bedrock (false or otherwise) and hopefully get the coil of the machine over some cracks or under the edge of some large rocks. Alternatively you could just snipe the crevices, but that means getting into the water.

Good luck out there!

Oh, one other thing. The time of year makes a big difference. The flow of a river in Jan/Feb is very different to the flow of the same river in June/July. Detecting when the water level is at its lowest will help you a lot.

[klunker]

 Be wise and don't outsmart yourself.  "No bedrock" doesn't necessarily mean "no gold". You have to stop and think about the big picture to find the little nugget.

[Norvic]

Research is good, but after 30 plus years of detecting gold, lots of armchair reading and dreaming, only one thing puts you onto gold consistently that is swinging the coil. If your in gold country as shown by mapping, and even outside it on the fringes, regardless of whether informed sources say the gold is too fine, is mixed in minute amounts in complex ores, is only on the out of reach bedrock or is all gone. There is detectable gold in reach of todays detectors on all gold fields, a bold statement true but a attitude that will put you onto gold. Attitude is king, swing that coil believing it is there always. Tis where tis!!!!!!

[boulder dash]

Your new, just stick to bedrock.

[Reno Chris]

Sometimes bedrock does not look like what you might expect. I've seen bedrock that is totally weathered and looks to the eye like clay, but the gravel is mostly quartz, so the gravel seems unchanged.

The other thing is that there is also "false bedrock" a layer of gravel or clay that can act like bedrock. Sometimes false bedrock can look like just a color change or a layer that is cemented, etc.

Bedrock is always clear and obvious.