This is what good Ancient River Dirt looks like for you new prospector's. Notice the black sand pebbles throughout the dirt and the orange 'rust' color of the surrounding dirt. Produces nice gold in your pan. If you don't see this-keep prospecting Mister.
When you spot ancient river, look at the bottom layer that is upon bedrock! That is usually the rich zone.In the Sierras, it is the "Big Blue Lead" and has packed gravels of a blueish tint. You will need a crusher to break it up!