By 1850, it was getting hard to find placer gold. That’s the gold found in rivers and near the ground’s surface.
As a result, placer mining gave way to lode mining, which goes deep into rock and minerals. Lode mining requires digging up mountains or drilling deep into the ground. The days of the placer miner were over. The era of big mining companies and industrial mining had begun.
Industrial mining methods soon took over. Hydraulic mining was highly effective, but it was very bad for the environment. Some of its effects can still be seen today in California’s mountains, rivers, farms, and forests.