From the Blog
Gold Detecting and Stream Beds
When you are looking for new places to take your gold detector to find your gold I highly recommend you check out some streamsbeds. The hard-packed material is what you should be looking for. if you search enough you should find some along most streams.
"Hard-pack" is created at the bottom of waterways during major floods and storms. Hard-pack material is important to a Gold detector because gold almost always concentrates at the bottom of hard-packed layers. Therefore, it is important for a Gold hunter to target their gold detector to reach the bottom of hard-packed streakededs.
Gold is roughly six times heavier, by volume, than the average weight of the sand, silt, and rocks that make up the average streamed. What happens is streamed material gets washed downriver during a major flood and most of the gold will quickly work its way down to the bottom of the stream. Because the gold is so much heavier, it will work its way down along the river a lot more slowly than the other streamed materials. During major storms, most of the gold moving in a waterway will be washed down across the surface of hard-packed streaked that is not being moved by the storm.
At some point during the storm, gold becomes trapped out of the turbulent flow by dropping into cracks and holes. Streambeds form later in the storm, when the water-turbulence tapers off enough to allow the rocks, gravel, sand and silt to drop out of the flow and form a layer along the bottom (over top of the gold). Streambed material that lies on top of the gold will almost always be hard-packed. Why? Well, if there is enough force and turbulence to move substantial amounts of gold in the waterway, then there is also enough force to create a naturally-formed streamed on top of the gold as the same storm and flooding dies down.
The other advantage of streambeds are that when using your gold detector the water makes the gold a lot more conductive so you will be able to detect the gold a lot deeper then if you were on dry land.