Hey everybody, tonight we’re going to talk about something related to what we’ve been discussing and floods and rains and what happens to gold. I cover some of this material in 20-20 prospecting (See: https:/Sourdoughminer.com/20-20/ ) as well.
We’re going to talk specifically about how changes in the stream flow effect placer gold deposits. So the objective here is just simply a kind of a chalk talk. I mean, he had spend some time on the blackboard going over how the things we’ve been looking at this last weekend because, you know, this has been a flood week, like shark week. And so, the idea here is let’s look at what happens as these floods go up and as they go down to the stream bed, I have some pictures in there that I’m showing, for example, this one that I’m showing on the side over here is basically a cobbles and the sample hole that I have, where I’m going down to bedrock through a bunch of layers that were laid down by various flood conditions.
Different layers had different amounts of gold. And so it’s important to understand a little bit more about how that happens and what that has to do with you. Because when you’re prospecting for gold, you want to be able to find those layers, understand how the effect, the golden it’s depositing and where to go next. After all, this was just the sample whole. We’re looking for the pastry can those conditions, so let’s take a look back to the front cover page.
Here. You can see the layers in this one structure. There’s sort of this concreted segment down below where it’s sandy clays and then there’s these routed cobbles that are sort of hovering up above in space and you say, how could that be? How can that happen – PJ? And the answer is FLOODS. Floods have certain properties and as they take place, those properties come into play and caused layers to be laid down.
There’s a little bit of understanding of the hydrodynamics and the slurry itself, the suspension of materials, and in a gravitational field that’s kind of floating, if you will, but they’re really not. They’re bouncing around on top of each other and the idea is if you understand a little bit more about how that works, you can understand kind of what causes this kind of a sill and where the gold would be in this situation. I’ll give you a hint. I’m pointing to it in the, in the center of the screen.
The idea is how did it get there and that I’ll talk about in a second here. So let’s go over to the blackboard for a second and look at stream flow and placer gold. So when we start off with a flood and we have some better reason, you know, pretty much we have a stream that looks like this and then kind of has a v shaped notch in the bottom and then another set of banks on the other side.
And so another idea is at some point the water’s flowing along under normal conditions and you know, there’s no flooding or there’s no, no fast flow or rapid erosion. And so under those conditions, this bottom might be covered with some material and in there might be suspended rocks and cobbles and various other smiley faces and there might also be some other interesting stuff that would give you some idea of where we’re going next and that is little pieces of gold here that might be buried at the bottom of this thing.
There also might be some out here you just don’t know, but the objective is we’re looking into the stream bed. This is bedrock over here, so really we’re not going to see anything over there away from bedrock where we’re going to see it mostly is in this bottom, but there’s a reason it got where it is and there might be some other reasons that it might be someplace else.
I’ll go into that in a second. It’s at normal conditions streams full might not be completely full in summertime. It might only be a filter to this point and it might just be a little tiny little tiny riffle of water in here flowing through and it might be and or back and forth in the stream bed. You just don’t know. But the idea is that’s how it looks when it’s under normal conditions. What we’re going to do now is take a look at what happens to this same stream bed when we start heading into flood flow. So under full load, full flood, there’s not going to be much down here at the bottom at all that the water level’s going to be at the top and if not flowing over the edges. And so under these conditions, there’s a huge velocity gradient across this thing going downstream as fast as it can.
So all those rocks and cobbles, the only ones that are going to be left are the biggest ones. Stuff that might not be moved. Everything else, silt, small gravels, etc. Speeding downstream, finding the nearest boulder to hide behind or some bushes or things like that that are tied to the edge of the creek and they’re going to hide there. But at this point floods scrubbed it to the bottom. And so under these conditions, the only thing left at the very, very bottom is going to be heavy, heavy gravels and some large chunky gold if there is any.
So the idea is that there’ll be gold buried right down to bedrock, so any gold nuggets are going to sit mainly on this surface here. So the idea is we want to understand what happens next. Well, as this flood starts to abate or slow down, then the conditions get interesting because what’s really happening here, if you look closely is, and I’m going to paint these in it in a kind of blue or green, but what we have here, the rest of the material which is zooming downstream as a slurry of material
and only the biggest cobbles are going to be caught on the bottom. The big boulders and maybe things that are trapped underneath those, but the rest of this stuff is going to be shooting downstream and any mud and silt. It’s going downstream as fast as it can. And with that goes any flour gold and he lighter gold.
So they’re find gold is hidden in here as a bunch of little particles that are just kind of scooting along with those flakes of gold and nuggets and rocks. Not nuggets. The rocks and and small particles of gold. The stuff that are nuggets are heavy and dense enough that they don’t get carried along with this thing unless it’s a full blown flash flood and then the dose conditions, those things can move, but otherwise they sit there and continue to concentrate over the years. The rest of this stuff going downstream and looking for a place where the water pools and slows down as it pulls and slows down, boom drops out.
So now let’s go to the next condition. So now we go to the next condition. When our stream starts to slow down and under these conditions, the water is receding. Okay? It’s not full, it’s not flowing over the sides and the particles and things are starting to mix in with those cobbles and boulders we saw on the bottom and fill in with silts and sands.
So there’s lots of little particles packing in here now. It’s still been vibrating as it’s going down. So what happens is this stuff has a chance to, to accrete they call it, which simply means to pile up and this is the stuff in the summer season or if it’s a stream that’s been suspended, it’s, it’s essentially going to lead you to what is called overburden. It’s the material. It has no gold or not much. The only gold that might have would be light flour gold. And so when we look at this stuff as it accretes, we’re going to see the gold is still down here.
It none of these rocks and cobbles, the big boulders and then there might be some more picker kind of gold right in here, but nothing big in a way of and way of bigger nuggets. They’re down on the bottom, on bedrock up. There is still some particles that are floating around with our friend the mud and silt. Okay. The brown stuff. And so it’s still floating out here, kind of working its way down to the bottom, but it’s still flowing fast enough that it hasn’t really settled out yet. So these flour gold particles are going to continue to go on downstream with the rest of that flow until they find a pool or something stagnant.
It’s slow enough that they can Begin to drift to the bottom. Does that make sense? So that’s an important aspect of how the flood transitions from a flood to still water or just a brook or a stream. And so now we go into the mode where we’re looking at a this intermediate flow, we continue to go down looking at the flow as it as it hits its normal flow as we were talking about where we are at summer level and that looks something like this.
And our water flow is way down here and our rocks and cobbles are still hanging in the bottom. But we might even have some material that has built up on the sides here. It’s mud, silt, sand and small gravels.
And buried in it might be a little bit of picker bold fine. Actually coarse gold, that has found its way into this material and deposited again toward bedrock. And our big nuggets are still going to be buried down here underneath the rocks, cobbles and boulders that are in the center. Now, why would they be in the center? Well, that’s because that’s where the torrent came through and ripped out everything else.
So the only thing that could stick with those big cobbles, big hint, If you see big cobbles; think big storm must’ve moved through here at some time. And therefore below those big cobbles can be some gold finding opportunity, especially as it heads toward bedrock or a false bedrock made out of clay. So any of these conditions can be interesting to you. Now under these conditions, one of the things you want to watch for is sometimes these things are just dry.
There is no water at all, but a lot of times the water’s just simply down in here, you know, flowing along in a little meandering stream that’s a brook running down the center line of this thing or not even centerline, kind of like a drunken sailor. It’s all over the place. It doesn’t represent, (key point.) It doesn’t represent the real flood flow that went through this valley. That’s why you need to know those high water lines we talked about last night or night before last.
Hey, if you’ve got an idea of where this high water is and you know where it’s settling the material out here by looking for these bigger cobbles, you have some idea of what’s going on, but notice it transitioned into this dropping these finer things. Oh, and by the way, way over in here in some corner would be a final pool. I didn’t show it here, but it would be a pool where it dropped out all the flour gold and typically with that you’ll find lots of sands that are heavy and black sands.
So that’s it for tonight. Prospector Jess over now, just thought I’d touch up and tell you where stream flow and placer gold connect. So good prospecting.
Hey, I cover some of this material in 20-20 prospecting (See: https:/Sourdoughminer.com/20-20/ ) as well. it’s part of that same training. So if you want to look for that, just go right ahead.
So I’ll catch you later.
Next transmission, coming from Hunting4Gold.com and Prospector Jess, over and out!