Usually round rocks come from being tumbled for a long time in a fast flowing river but just because you can see round rocks does not mean the part of the river that could have gold in it has been exposed yet. Same rule applies sample, sample, sample so this means small scale work taking 2.5 gallon samples from several locations and panning out the samples of course keeping the samples marked so you know where along the hillside the samples came from. And of course, good luck in your search!.....................63bkpkr