It only takes a small amount of water force to move sand-sized particles downstream in a riverbed. There is a massive amount of gold in gold-bearing waterways which is so small in particle-size that it floats in a state of suspension in the river water itself. Some amount of gold is moving downstream in any gold-bearing river at any given time. An increase in water-flow increases the amount of streambed material and gold that is moved downstream.
Normal winter storms, for the most part, can move large amounts of fine and ultra-fine gold.
Today’s modern river-prospector is mostly interested in that gold which lies inside and underneath naturally-formed streambeds. For the most part, this gold will remain locked in place until a storm of major proportions comes along. Such a storm can cause so much water force in the river that large sections of pre-existing streambeds, and the gold that is within them, are swept up and washed downstream.
When a storm or snow-runoff of huge dimensions comes along and creates so much water force that large portions of the riverbed are torn up and washed down along the bedrock, large portions of the bedrock will also get pounded loose, and any gold that was trapped in that bedrock will be washed further downstream along with the rest of the streambed material.
The amount of gold still sitting inside streambeds of gold-bearing rivers is incalculable, but it’s a lot! Much was left behind in low-grade deposits which the early miners were not capable of mining at a profit. While there may have been a lot of gold in some sections of river, it might also have been too widely dispersed or sitting under too much over-burden to make the gold worth mining in those days. Other very rich deposits were missed because they were out of sight. Without processing every inch of streambed ( which they did not have the capability to do) the old-timers simply could not find all of the gold deposits that existed during their time. A lot of gold that was excavated was never recovered. It was washed out of the high streambed deposits, through sluice boxes, and right back into the present rivers and creeks. This was particularly true of hydraulic mining, where an estimated 59% of the gold was missed by many of the large and small operations alike.
Also, in the last 150 years of erosion, more gold has been washed into the present rivers and streams out of higher and older streambeds, and out of some lodes that are still in existence. In taking all of this into consideration, we are talking about a lot of gold still sitting in these gold-bearing rivers. In some cases, there is more gold now than the amount that has already been mined out of them.
When a major storm occurs and tears up a large portion of streambed, a great deal of gold is set free and put into motion downriver. A fair amount of this newly-released gold will be deposited in common areas along the riverbed. This is the type of gold that the modern prospector should be sampling. The same major storm which causes enough force to tear up large portions of streambed will also deposit most of the material into newly formed natural streambeds, even in those same areas that were once previously mined.
During full flood stage, when streambed material and gold are moving free in the waterway, because it is so heavy, most of the gold will travel along a rather narrow path. This path is often referred to as the “gold line.” Almost all high-grade paystreaks will be located along this specific path. Therefore, the first step in prospecting is to locate where the common gold path is in the waterway.
Normal winter storms do not create enough force to do this. A winter storm might be enough to sweep up small portions of riverbed, but this small amount of movement is not likely to put paying quantities of gold into play in the riverbed. However, most gold-bearing areas have had at least one of these major storms since the early 1960’s.
When millions of tons of rocks, cobbles, and boulders are being swept downstream along the bedrock foundation during a huge storm, the ground shakes and vibrates, and the river rumbles like a huge loaded freight train.
Streambed layers caused by different flood storms are referred to as “flood layers.” Flood layers within a streambed are easily distinguished, because they are usually of a different color, consistency and hardness from the other layers. Sometimes the bottom of a flood layer will contain more gold than is present on bedrock. Sometimes, when more than one flood layer is present, there will be more than one more layer of flood gold present as well. Gold deposits can also be found in the contact zone between the layers.
Flood layers that are caused by major flood storms are almost always found in a compacted state where the rocks and material hold together tightly and require tools to pry them apart. In mining, we call this “hard-pack.”
Some of the best to test for paying quantities of flood gold are where the stream or river widens out, or levels out, or changes the direction of its flow. Gravel bars, especially the ones towards the inside bends, tend to collect gold. Flood gold in bar placers is sometimes consistently distributed throughout the entire gravel bar. Often the lower-end of a gravel bar is not as rich as the head of the bar, but the gold there can be more widely dispersed.