Blind Bedrock Profiling

[Underburden]

Blind Bedrock Profiling A Creek Side Bench
I have a large bench next to the creek on one of my claims. Digging with a shovel to determine depth to bedrock was way too time consuming and hard on an old man's back. This year, I'll be 'Probing' for bedrock depth. This bench was made up of a foot of sod, then two feet of clay/mud and finally, when the hole was less than a foot in diameter, rusted river gravel...and still no bedrock.

This is what I'll be using this summer. Simple steel fence post with the bottom blade cut off and the tip cut at a gentle angle. The horsepower to drive the post will be my trusty fence post pounder.

This illustration will help explain my plan.
Bob

 

[timberjack]

I saw a viedo where a fellow used a gas powered post hole digger (drill type). He had some 4 inch bits that tou could keep adding sections to as he went deeper. Always wonderd it an ice auger could be fitter with a 2 or 4 inch bit to accomplish this task..seems like large rocks would be a real problem.

 

[63bkpkr]

Finding Bottom

First good idea and the 'T' fence post is a lot lighter than a solid bar of the same length. I would suggest breaking out your handy dandy Harbor Freight angle grinder to remove some to most of those knobs that are used for binding wire around so the fence does not slip much. My thinking is that they will cause a great deal of friction when pulling the probe out of the ground/rocks/rusty gravel. Bustin a gut getting it in and busting two guts getting it out as now it is all up to your legs, upper arms and your Back, do not want to mess up the back. If removing it from the ground becomes a big problem then i would use an old bumper jack and a piece of chain to get the T out of the ground or else one of those HEAVY duty 48" farm jacks but they are heavy.

Good success with the project! 63bkpkr

 

[Underburden]

Been pulling fence post around my property with a #2 shovel for years.
Slip the tip of the shovel under a knob then push down on the end of the shovel handle.
Post comes up a couple inches, reset the shovel on the next knob and repeat.
DONT grind those precious knobs off
Bob

 

[Bejay]

Well it looks picture perfect. I am not sure how many posts you are going to have to drive to get a good picture of how the bedrock is looking. If that does not work try jetting down 1 inch galv pipe. Put a jet nozzel on the end and hook it to a jet pump..... like one on a dredge. I have jetted down through dirt and sand and small gravels.....but not tried large compacted gravel.

Anyway good luck with your posts.

Bejay

 

[Rob in KS]

That still sounds like it'll be hard on an old man!! I can only pound about 4 and I'm done in, and I don't have rocks to contend with. Around here, you can't pry them up with a shovel especially if the ground is wet. That bumper jack idea sounds like a good one.

 

[Underburden]

One fence post. Drive it and mark the post where it stops going any deeper. Annotate in a notepad.
Remove post and move a foot or so and drive it again...marking the post again. The notepad will start to show a graph.
Around my property, the ground is clay that solidifies like a brick when dry. I pull after a good rain...lots easier then.
P.S. They come out a lot better without that stupid blade at the end of the post

 

[MadMarshall]

It looks good on paper.. But useful I sincerely doubt it.. Bedrock doesn't always mean gold. Lots of made up work for nothing.. Let me just say I spent years crawling on Bedrock and Find this notion of Profiling Bedrock pure Tom FOOLERY..

I let the Gold do my profiling... Not hopes and Guesswork.
Sample Sample Sample..

 

[Goldwasher]

Underburden what you propose to do is sampling. It is a common thing to drill holes and run test holes to determine depth of bedrock and pay layers. Some people forget that others are in different situations. maybe you are gonna high bank and your area doesn't have the types of cracks condusive to productive sniping. Maybe you will hold this ground for years to come and want to map it out long term. You have left out some information, maybe if you mentioned more MM wouldn't make such a rude comment. Maybe all your good days have come from running gravel and you enjoy it. Maybe you do hit your bedrock and have found color and your just looking at the big picture. I could see your plan helping you chase your bedrock. My only concern is that I would center out my probe in a big rock and believe it was bedrock. I sometimes forget that there is only one real gold miner on this forum, and the rest uf us are just wasting our time....so I guess you will have to wait until Game of Thrones is one again to find out what you should do and how you should do it. Until then your just gonna have to continue being foolish I hope you can live with yourself.

 

[Fullpan]

Setting aside the cost of technology, - is there a machine that can scan gravel bars and show the contours of the bedrock below ?

 

[Clay Diggins]

It looks good on paper.. But useful I sincerely doubt it.. Bedrock doesn't always mean gold. Lots of made up work for nothing.. Let me just say I spent years crawling on Bedrock and Find this notion of Profiling Bedrock pure Tom FOOLERY..

I let the Gold do my profiling... Not hopes and Guesswork.
Sample Sample Sample..

I once knew a guy who was convinced that you couldn't find gold anywhere there wasn't pink granite. I'm pretty sure he knew everything about prospecting too. I wonder why he would disagree with you Victor?

Several of the mining companies I work with waste a lot of time and money profiling bedrock. They put that down on their expense sheets as sampling.

Good luck in Alaska.

 

[Bejay]

So here is the trouble with the bedrock probe:

It is limited to basically finding the depth to bedrock. If one does a core drill then one can determine values through the overburden to bedrock.

For all us old salts who have been chasing the bedrock for umpteen many years we know gold can be pocketed in specials spots/places on the bedrock.

It sure would be nice to be able to see where it is lying down under all that overburden...but it ain't happening; unless one has unlimited $$$$$.

Bejay

 

[Clay Diggins]

For anyone serious about perfecting their placer mining claim I strongly suggest you look into defining your deposit by drilling. It's been the industry standard for more than 100 years.

Before you go off about expense and permits and how it's just not feasible for the little guy please consider the low cost, low tech Banka Drill.

Look around the website. It won't cost you anything but it might open your eyes to the possibilities.

These things are so simple that you could get 10 year olds to line up to take their turn. Free labor! No permits! Nothing for a greenie to complain about. And CHEAP!

A group of nearby placer claims could easily rent one of these and cooperate to sample drill all the claims in the group in under a month. The results, used with discretion, will tell you rather precisely where the bulk of your deposit is, what depth holds the best paydirt and how much your deposit is worth.

I did quite a few samples with a 4 inch Banka in the early 80's. Three strong young bodies and enough sense to make a chart and map plot of your results and if you really do have a valuable mineral deposit you can prove it to all who might challenge you. Test all the ground on your claim and you might just be surprised where the gold is actually worth digging. (hint - it's not all in the stream)

Oh yeah - they will profile bedrock for you too.

 

[MadMarshall]

The simple fact is that most people who are reading those articles are only armed with shovels and sluice boxes high bankers ect ect... I suppose for some the most common prospector can't afford nor wishes to move a crap load of overburden just because of some possible pocket that maybe has his labor in gold or any at all for that matter.. I move gravel to get to bedrock sometimes but not blindly and most certainly not because I put any real stock in such genralizations like these.."Any time bedrock drops suddenly, an opportunity for good gold accumulation is created."..
A lot of differences between small scale prospecting and these larger companies.. but regardless.. that method of profiling bedrock is very poor at best.. just truth...