The Tillinghast Preserve was donated by Harriet T. Fuller and Alice S. Tillinghast at the end of 2002. It was the land trust’s 23rd preserve and its first in Plainfield. Sugar Brook forms the eastern boundary of the 34-acre preserve, and it abuts the State’s 1618-acre Quinebaug River Wildlife Management Area to the west.

Part of the preserve was formed by an esker, a gravel ridge deposited in a meltwater channel beneath a stagnant or retreating glacier. Many eskers have been mined for their rich gravel deposits, but this one is now preserved.