Northfield Mountain, 1,206 feet (368 m), is a mountain ridge located in Erving and Northfield, Massachusetts. 2.5 miles (4.0 km) long by 1.8 miles (2.9 km) long, the mountain is composed of several distinct peaks and ledges, most notably Rattlesnake Mountain (also known as Farley Ledge) 1,067 feet (325 m), Rose Ledges 1,080 feet (330 m), and Hermit Mountain (the high point).