Dreaded Gold Rush Dredge
Had there been any environmental laws around the turn of the century there may not have been a gold rush. Then again, the gold rush from the turn of the century up to the 1960's may have ushered in environmental laws. The landscape for miles around Dawson City, Yukon has been dramatically, and permanently changed by gold Dredges.
I was always under the impression that the gold rush was led by old prospectors with picks, shovels and pans. It may have started that way but the whole process became very industrialized early on with the introduction of the dredge.
The idea of the dredge is to scoop up all of the soil and rock above the bedrock and shake the gold out of it before depositing it back onto the ground. See schematic below.
The dredge would follow a stream in a valley. It would float in a pond that it created by dredging sediment. As it dredged, it would move forward slowing destroying everthing in its path and leaving piles of spoil in its wake. The pond it created would follow along under it.
One of the dredges, Dredge No.4, is well preserved and remains where it sank in 1959 on the Bonanza creek, Yukon. It has been named a national historic site.
These are some of the 72 buckets that were used to scoop up the soil. The dredge was designed to process 22 buckets per minute.
The interior of the 8 storey tall dredge was huge. Giant electric motors and pulleys were key to the dredges operation.
Once on board, the ore was washed with water from the pond and driven over shaker bed from which the heavier gold would drop out. The beds were lined with coconut fibre mats to collect the fine gold. The mats would later be burned to release the gold.
Remarkably, it only took a crew of eight to run this giant machine.
This same dredging technology was used all over North America. We ran into another dredge in our travels that was located in Idaho. It looked pretty familiar.
They are still mining the Bonanza Creek in the Yukon. This is what the operations look like today. Same principles in use. Its just that its done one bucket at a time instead of 22 per minute.