 Newer rivers and streams then developed, and some of these cut through the old channels, carrying the gold into still larger concentrations.The Forty-Niners of the California Gold Rush first focused their efforts on these deposits of gold, which had been gathered in the gravel beds by hundreds of millions of years of geologic action.Because the gold in the California gravel beds was so richly concentrated, the early forty-niners simply panned for gold in California's rivers and streams, a form of placer mining.