When you think about pot holes, you probably picture annoying driving hazards in the middle of the road that you try to avoid at all costs. That hole in the asphalt can cause a flat tire and help throw your car's alignment out of whack!  But a pot hole in a rock that's located in a gold-bearing stream or river is something you DON'T want to steer clear of the next time you're out prospecting.

One way a natural rock pot hole is formed is when sand, pebbles and small rocks are spun around on bedrock by river currents. As they spin, they work like a drill and slowly grind away at the rock. In the process, the stones and pebbles caught in the hole wear away at themselves as well as the bedrock until they are swept away by the current and replaced by other pebbles, sand... or bits of GOLD!  This type of natural drilling has taken place in most California rivers for thousands of years, but you can expect to find potholes in just about any river that has a rocky bed, especially if it's made of limestone, granite, or lava. Some holes are a few inches in diameter and depth, others can be quite large.