The huge, unsightly piles of gravel waste in the beds of many creeks in the western states are evidence of the use of enormous floating dredges to work the gold-bearing gravel back in the early days. These monsters inched their way up the creek bed, gobbling up the earth and discharging the gravel behind them. In their day, they were fairly efficient machines. One by one, however, they fell into disuse due to increased operating costs and the fixed price of gold. Some were dismantled and shipped to other countries where operating costs were lower, but others have remained on the site of their last operation as ugly reminders of that period in the history of placer gold mining.
Typical of these huge floating dredges is one near the highway in a pond on a small creek near Jefferson City, Montana, between Helena and Boulder. A picture of this representative of these old dredges is found on page 50.
Portable Floating Dredge: There is a modern, lightweight, portable version of the floating dredge which is both inexpensive and efficient. It combines scuba diving gear; a rubber raft or other platform; a light, efficient gasoline engine; suction equipment; and a portable sluice box. These dredges work on the same principle as a vacuum cleaner and can be used in ponds, rivers, or creeks.
Initial underwater exploration can be done with a snorkel, to avoid setting up the floating dredge if the location proves to be unfavorable. The objective of the floating dredge operator is the same as the crevice man, except that he is working underwater. In addition to suction equipment, he often uses crevice tools to work the deep and narrow cracks where the gold is most likely to be found. The vacuum hose of the suction dredge picks up and delivers the sand and gravel from the crevices and other traps to the upper end of the portable sluice box on the floating platform.
This method of mining placer gold was not even dreamed of by the old prospectors of the early days or miners in the Depression days of the 1930’s. With equipment such as this, the modern gold seeker has an enormous advantage over the miners who have gone before him.