Stream Placer

In order to discuss what happens when gold gets into a creek, first it is necessary to understand the terms “bedrock” and “sediments.”

Some million years ago, the external perimeter of the Earth cooled off and hardened turning the surface into solid rock. This is called “bedrock” (or country rock when referring to lodes). All the loosened earth, rock, sand, gravel and stones that rest on the surface of the hard-rock of the Earth is called “sediments.”

In some areas sediment material is hundreds of feet deep. In other areas, especially in the mountain area and on the seashore, the external layer of the Earth is completely exposed. One can usually see the bedrock, transversal cuts on hard rock that have been made so that the highway can run straight and leveled, when driving on a highway.

The streambeds are formed by rocks, sand, gravel, clay and stone (sediment) and always rest above the bedrock foundations. Bedrock and country rock are the same thing.

A great storm in mountainous areas will cause creeks and rivers from the area to run deeper and faster than they usually do. The additional volume of water increases the force and turbulence that flows on top of the streambeds that lay under the waterways. When strong storms happen, the force of water sometimes increases so much that it is enough to sweep all the bed through the surface of the bedrock foundation below. It is this action that causes the streambeds to sink each time more in the Earth for a long period of time. A storm of this strength can also erode a considerable amount of new gold towards the inside of the beds where it will mix with the other materials.

Being gold heavier than other materials that are swept downstream during the storm will quickly locate itself under them. The reason for this is that gold has a higher specific gravity than he other materials of the streambed and that is why it will put pressure against them towards the bottom.

While the bed is being shaken, pushed and hit from all sides because if the tremendous stream of water caused by the storm, gold will vibrate downwards going past the rest of materials until reaching a limit, which would be the bedrock.

Except for the tiny pieces, it takes lots of effort t move gold since in average it is six times heavier than the rest of materials that commonly lie on the bed; and it takes even more effort to move gold through bedrock than any other materials from the bed.

Therefore, there is a possibility that there will be a section in the river which is stronger sweeping part of the bed due to the storm, and maybe not so much strength so as to take the gold lying there.

When there is a force strong enough to move gold through a streambed that gold can be deposited in a new location in which the strength of the stream is less.