As long as the water pressure is high enough to move the gold, it will continue to move. We’ve talked about curves and their effect on water pressure, and we’ve also talked about objects that water must flow around, like boulders. We’ve also talked about the fact that gold crawls along the bottom of the river bedrock. It will continue crawling along the bedrock as long as the water pressure is high enough to push it. Two conditions can present themselves to stop the gold from moving down the riverbed.
The river bedrock can be rough, jagged, and craggy where gold will “hide” from the high water pressure.
The river bedrock will have cracks and crevices that the gold will drop into.
Once the gold has found one of these locations, it will remain their until either the bedrock is broken up by water action, earthquakes, or the pounding of large boulders as they are moved down river.
Smooth bedrock give the gold no place to hide from the forces of the water pressure, and so it will continue down river until it does find a hiding place.
So, if you dredge in a location and reach bedrock, but the bedrock is smooth, move to another location. It’s always possible you may find the occasional nugget, but more than likely, your wasting your time. If, however, the smooth bedrock has cracks and crevices for gold to drop into, work them.
A crack in the bedrock does not have to be large. Wafer thin pieces of gold will work their way down into even the smallest cracks. It is well worth your will to open these cracks and clean them out. In fact, clean them out two or three times. Use both the high pressure water jet tapped off the water pump and crevice cleaning tools.
Cracks that look very thin can also open up farther down making a large pocket for gold to accumulate. An amazing amount of gold can come out of a crack that doesn’t look like it could hold any. Do Not pass up any cracks or crevices in the bedrock.
Gold moves when water pressure is high enough to overcome the weight of the gold. When the water pressure decreases, gold stops. It can hide behind an object that has broken the flow of water, or it can fall into a crack or crevice and hide from the water pressure. It can also stop when water slow down to flow around the inside of a curve. A fourth place is where the river widens into an area of slow moving water (commonly called a pool).
Let’s consider a specific quantity of water. When that water moves through a area that is 25 feet wide, it moves at a certain speed. If that same quantity of water moves through an area that is 100 feet wide, it slows down. Just like what happens when a river flows into a lake.
When the gold is pushed through the narrow region in the river, it moves at a certain speed. When it enters the pool the water slows down, the water pressure is decreased and the gold drops. So, there will be an area at the beginning of the pool that will have good gold. It will probably be evenly distributed across the width of the pool, so look for places where the gold will pocket (exposed bedrock, boulders, cracks, crevices, etc).
The above discussion will give the novice prospector a good idea of how to read a river to find where gold will “pocket.” Of course, you ca follow each of these lessons in detail and still not find a lot of gold. First, make sure your looking at a river that is known for gold. The old timers didn’t get it all, but if a river has some, they found it. So, don’t waist your time looking in a river that has never had gold in it.
Practice reading rivers to see where you would dredge, even if you don’t plan on dredging in it right now. As with any skill, reading a river and finding gold takes practice. Talk to those who know the river. They can save you a lot of looking time. If possible, join a club that has some claims for the members to use. Clubs also have “outings” at which you can learn even more and actually participate in the “common operation.” That way, you can get experience without wasting time. Let the club experts figure out where to work, then ask them why they chose that spot. Having some on the ground instruction can go a long way.
But, if you don’t have a nearby club, and no locals will break loose with they’re secrets, then follow what you’ve learned here.
More tips on Dredging Gold:
Do not run your dredge motor without an air filter. Even though it may not look dusty, microscopic dust will score the intake valve and the combustion chamber, greatly reducing the life of the engine. Change the air filter a minimum of once per year.
Tip # 2
Change the engine oil after the first 5 hours on a new motor. This is “break-in oil.” After that, change the oil every 20-25 hours running time. Typical dredge motors do not have an oil filter, and the oil must be changed more often than your car. Use ONLY grades and weights of oil recommended by the manufacturer. For Briggs & Stratton engines, ONLY 30W detergent oil (not 10W-30 and not non-detergent oil).
Do not leave the dredge engine’s gas tank empty, even overnight. When done for the day, top off the tank with fuel to prevent condensation from forming in the tank.
To store the dredge engine at the end of season, hook a water supply to the pump (do not run dry). Fill the tank with fuel treated with a fuel stabilizer, such as STABIL. Run the engine for 5-10 minutes. Cover and store in an area not susceptible to gas fumes buildup.
When dredging, only run the engine as fast as necessary to provide good suction at the nozzle…not (necessarily) wide open. You want good suction to pull the solids all the way to the sluice box, but decreasing the speed of the water provides better separation of fine gold.
When operating the suction nozzle, don’t “jam” the nozzle into the gravels. Doing so will cause frequent plug-ups and overfeed the sluice box. The ratio of water to solids should be about 3:1 (3 parts water to 1 part solids), but no more than 2:1.
Don’t try to max out the size rocks that go up the suction nozzle. Even though you might have a 4″ nozzle, letting a 3 3/4″ rock to go up the hose will have a good chance of getting lodged and plugging up the hose at the joints. Instead, take the extra time to pull them out of the way.
Take a round file and taper the inside of the jet tubes. This little amount of tapering can help in prevent many plug ups.
Use ribbed carpet under miner’s moss in the sluice box. This will do a better job of catching fine gold better than miner’s moss or ribbed carpet by themselves.
Keep a roll of duct tape (100 mph tape) handy. Good quality duct tape can seal holes in your suction hose, make temporary repairs to pontoons and other dredge parts, and a host of other uses.
Paint all tools bright florescent orange. Tools are much easier to see when they are bright orange instead of black. This is especially useful when working in murky water.
Take only the tools down that are necessary for the job. In taking too many tools underwater, you run the risk of losing accountability. Tools can be covered with cobbles easily.
Use a rubber “dead blow” hammer (2 1/2 lbs) to assist in unclogging the suction hose. The rubber head will not damage the hose and the “dead blow” design gives that extra punch.
Repair holes in your suction hose as soon as possible. Gold “crawls” up the hole and can fall out of a hole in the hose.
Keep a bottle of isopropyl alcohol handy just in case gas or oil are spilled in the sluice box, cleanup tubs, classifiers, pans, or anything else used to process concentrates.
If you see an oil “sheen” anywhere in your concentrates, use one or two drops of dishwashing detergent to break up the oil.