The town was founded as a mining camp on the banks of a seasonal stream known as Aqua Fria. This original town site was located about to the west of present-day Mariposa. Prior to this, Southern Sierra Miwuk resided in the area. After a flood during the winter of 1849/50, and fires, the town was moved to the location of today's Mariposa, although mainly due to better terrain and the presence of Mariposa creek, a large producer of placer gold. The gold in small Aqua Fria creek was soon removed, and lacked water most of the year. So the populace moved on to the new boomtown. The large Mariposa mine soon opened, with a 40-foot waterwheel crushing gold ore. This provided a stable source of employment, and Mariposa soon became the supply hub for hundreds of outlying mining districts. Placer gold, that which is found in creekbeds and alluvial deposits, was soon extinguished, and the era of hard rock, deep mining began. In 1851 the "new" town of Mariposa became the county seat of the county of Mariposa, which reached nearly to Los Angeles. By 1854 Mariposa had a grand courthouse which is still in operation. Some refer to the lumber being cut from an area to the east of town known as "logtown" but no maps or certifiable sources can attest to the existence of Logtown. Most likely the lumber for the courthouse was milled in Midpines, where there was an unusual abundance of sugar pine trees.