Hydraulic mining, or hydraulicking, is a type of mining that uses water to displace rock material or move deposit. Formerly, the use of a huge volume of water had been urbanized by the Romans to take out overburden and then gold-bearing debris as in Las Médulas of Spain, and Dolaucothi in Britain. The method was also used in Elizabethan Britain for developing lead, tin and copper mines, and became called as hushing.
The current form of hydraulicking, using jets of water directed under very elevated pressure via hoses and nozzles at gold-bearing upland paleogravels, was initially used by Edward Matteson near Nevada City, California in 1853. In California, hydraulic mining frequently brought water from elevated locations for long distances to holding ponds numerous hundred feet above the region to be mined. Insofar as California hydraulic mining exploited first and foremost river gravels, it was one type of placer mining that is, working of alluvium (river sediments).
Process of hydraulic mining
Early placer miners in California found that the more gravel they might process, the more gold they were probable to determine. Instead of working with pans, sluice boxes, long toms, and rockers, miners collaborated to determine ways to process bigger quantities of gravel more swiftly. Hydraulic mining became the vast-scale, and most devastating, type of placer mining. Water was redirected into an ever-narrowing channel, in the course of a large canvas hose, and out a giant iron nozzle, known as a "monitor." The tremendously high pressure stream was used to wash complete hillsides through huge sluices. By the early 1860s, while hydraulic mining was at its height, small-scale placer mining was a thing of the past. The huge majority of lone prospectors could not uphold themselves, and the mining industry was taken over by great companies, most of which discovered hard rock gold mining (or quartz mining) more gainful. By the mid-1880s, it is predictable that 11 million ounces of gold (worth around US$7.5 billion at mid-2006 prices) had been convalesced by hydraulic mining in the California Gold Rush.
Environmental effects of hydraulic mining
While generating millions of dollars in tax revenues for the state and supporting a huge populace of miners in the mountains, hydraulic mining had a devastating result on riparian environments and agricultural methods in California. Millions of tons of earth and water were carried to mountain streams that fed rivers running into the Sacramento Valley. Once the rivers reached the fairly flat valley, the water slowed, the rivers broadened, and the sediment was deposited in the floodplains and river beds causing them to augment, shift to novel channels, and overflows their banks, causing main flooding, particularly during the spring melt.
Cities and towns in the Sacramento Valley experienced a mounting number of devastating floods, while the rising riverbeds made navigation on the rivers gradually harder. Perchance no other city experienced the boon and the bane of gold mining to the extent that Marysville. Located at the confluence of the Yuba and Feather rivers, Marysville was the last "jumping off" point for miners heading to the northern foothills to hunt for their fortune. Steamboats from San Francisco, taking miners and supplies, navigated up the Sacramento River, then the Feather River to Marysville where they would unpack their travelers and cargo. Marysville ultimately constructed a multifaceted levee system to guard the city from floods and sediment. Hydraulic mining really aggravated the problem of flooding in Marysville and shoaled the waters of the Feather River so sternly that some steamboats might navigate from Sacramento to the Marysville docks.
The stunning eroded landscape left at the site of hydraulic mining may be seen at Malakoff Diggings State Historic Park in Nevada County, California. A comparable landscape may be viewed at Las Médulas in northern Spain, where Roman engineers hydrauliced the wealthy gold alluvial deposits of the river Sil. Pliny the Elder mentions in his Naturalis Historia that Spain had intruded on the sea and local lakes as an outcome of hydraulic operations.