Jeff Williams from http://www.askjeffwilliams.com/ shows you that the idea is to find a bench or bank that is in the right bend.
The California Gold Rush began at Sutter's Mill, near Coloma.[4] On January 24, 1848 James W. Marshall, a foreman working for Sacramento pioneer John Sutter, found shiny metal in the tailrace of a lumber mill Marshall was building for Sutter on the American River.[5] Marshall brought what he found to John Sutter, and the two privately tested the metal. After the tests showed that it was gold, Sutter expressed dismay: he wanted to keep the news quiet because he feared what would happen to his plans for an agricultural empire if there were a mass search for gold.[6] However, rumors soon started to spread and were confirmed in March 1848 by San Francisco newspaper publisher and merchant Samuel Brannan. The most famous quote of the California Gold Rush was by Brannan; after he had hurriedly set up a store to sell gold prospecting supplies,[7] Brannan strode through the streets of San Francisco, holding aloft a vial of gold, shouting "Gold! Gold! Gold from the American River!"[8]