Joseph Elgar built a saw and grist mill on Rock Creek, later known as Muncaster Mill. Muncaster Mill was built in the early 1800s and closed in 1925 due to competition from more modern milling practices. It was burned to its foundation in 1935. Muncaster Mill was the last mill to operate in what is now Rock Creek Park. During its lifetime, the mill served 30–50 farmers in the area. There were three millstones, each designed for a specific grinding job: one ground unshelled corn for animal feed; one coarsely ground wheat, barley, and oats; and one ground fine flour. For many years, there was also a sawmill, operated by a water turbine.