Down Stream from a
Tributary Stream 

A tributary stream is a stream that flows into another stream or river. Streams can have any size and can range from small ones that only flow in rainstorms to great rivers that flow all year round.

In most cases tributary streams have a slightly steeper gradient than the stream they flow into. In other words, it has a greater speed and is able to carry more gold because of its velocity and the effects of more gravity. Consequently, more gold going inside the tributary stream is carried to the main stream and is then carried by the main stream.

This denotes that right after the gold goes into the main stream it is going to become deposited and normally held close to the mouth of the tributary stream.

So how do you know how far downstream the gold can be found though? This mainly depends on the speed of the tributary stream in comparison to the speed of the main stream. This is obviously something that an expert will be able to tell accurately; nonetheless you can rest assured that there will be gold downstream at a certain distance. Bedrock and near bedrock placers are also located this way and they are good places to prospect in.

Eddies
Eddies are quite peculiar and are not fully understood. In order to understand how they accumulate gold you can do a little experiment. Try placing a spoon in a glass that is half full of water. Start mixing the water and then take the spoon out of the glass while the water is still swirling. You will be able to see that the water rises on the outside of the glass and that there will be a depression in the middle, you have successfully formed an eddy, congratulations and this is how the water in an eddy looks like and functions.

When the water is pushed up and out, the suspended material is undergoing the same process. Obviously some of the material that is suspended is heavier and will stay closer to the center of the eddy.

When the stream has flooded an eddy will speed up and will usually end its surface motion while the water level goes up and covers the eddy. Even though it can no longer be seen from the top, the eddy may still keep on swirling under the water and will create a whirlpool effect.

When there is flooding the eddy is given suspended material by the speed of the stream. The material is twirled around and the material that is lighter is thrown to the outside of the eddy where it is caught by the stream and is then carried away.

The material that is heavier has a tendency of remaining close to the vortex of the eddy. When the stream starts to decrease from the flooding stage the eddy then begins to slow down and the material that is heavier is placed and deposited in a place where it is then retained and accumulated.

There are actually two different types of eddies, one is a pressure eddy and the other is a suction eddy. Pressure eddies are formed when water of a stream pushes contrary or against an obstruction – this obstruction can either be natural or artificial. Suction eddies forms when the pressure in a stream passes from an obstacle quicker than the water is able to fill the space up. Both of these eddies can be a bedrock placer and the ones that can be defined well are usually productive when they are worked to bedrock.