The city earned the nickname "The Golden City" in the 1850s. The gold rush population peaked at almost 60,000, mostly male diggers, by 1858. However the early population was largely itinerant. As quickly as the alluvial deposits drew prospectors to Ballarat, the rate of gold extraction fluctuated and, as they were rapidly worked dry, many quickly moved to rush other fields as new findings were announced, particularly Mount Alexander in 1852, Fiery Creek in 1855, and Ararat in 1857. By 1859, a smaller number of permanent settlers numbering around 23,000, many of whom had built personal wealth in gold, established a prosperous economy based around a shift to deep underground gold mining.