The word placer is Spanish for the sand, silt, and soil scoured from the earth's surface by the action of water over time. Placer mining refers to the collection of minerals - in this case gold - from these alluvial deposits, generally in river beds.
Placer mining was generally done with the assistance of water. In its simplest form individual miners used a pan or cradle to gently wash away sediment leaving heavier pieces of gold in the bottom of the device. Groups of miners often used a sluice, diverting water through a gently inclined wooden channel, again washing the lighter sediment back into the nearby river or stream and hopefully leaving the heavier gold. On a larger scale as more capital was invested in California mining operations, hydraulic mining using large water canons, or monitors, became a common practice. The monitors ripped the soil from river banks where it had been deposited over eons washing it to collection points where it would be moved and processed.
The excerpt linked below from the diary of William Henry Hart paints a bleak picture of work of the individual miner, a life portrayed graphically in the 1852 drawing by J. Cameron entitled The Yankee House. As you study each consider the impact that individual miners had on the California environment they worked.
To Start You Thinking -
1) List the specific ways in which these individual miners altered their environment.
2) The white population in El Dorado County where these miners were working the American River and its tributaries grew from next to nothing in 1848 to over 20,000 in the 1850 census. Not all were miners, but most were. Describe the impact on the environment you might have seen walking along the mined river beds of El Dorado County in the early 1850s.
3) What would have been the cost of provisions per year for 15,000 miners based on Hart's estimate?