Placer gold is found in rivers and near the ground’s surface. By 1850, it was getting hard to find.
So people did less placer mining. Lode mining became more common. Lode mining digs up mountains and drills deep down. Placer miners were out of luck. Big companies that did industrial mining took over.
One industrial mining method was called hydraulic mining. It was the most powerful way to mine gold. But it was very bad for the environment. We can still see its effects today in California’s mountains, rivers, farms, and forests.
