Clark Reservation State Park is a state park in Onondaga County, New York. The park is in the Town of DeWitt, south of Syracuse. It was the site of a large waterfall at the end of the last Ice Age; the plunge basin at the base of the old falls is now a small lake. James Macfarlane described the area in 1879, "On approaching the lake from the turnpike on the south side, the tourist is startled at finding himself, without any notice, on the brink of a yawning gulf, precisely like that of the Niagara River below the Falls, and nearly as deep." Clark Reservation is also noted for its many ferns; it harbors the largest population in the U.S. of American hart's tongue, which is so rare that it was declared endangered in the U.S.