In the early days in Dawson the gold was in the creeks and easy to find but as time went on that source dried up and then mines were dug and then water canons were used to wash the paydirt down to settling ponds were it was seperated from the gold and later the giant dredgers came in they dug themselves lagoons and excavated as they went along,they were giant floating buildings processing the the ground and separating stones and soil then finally the gold and spewing the waste at the rear of the dredger known as tailings,these can be seen clearly on google earth at dawson alaska(abbreviated to ak)