Cushetunk Mountain, located in Clinton Township, Readington Township, Franklin Township, New Jersey, and Raritan Township, New Jersey is a horseshoe shaped mountain with the tips of its two prongs ending in the west at the edge of the New Jersey Highlands. The mountain's U-shaped arc is approximately in diameter, with the more massive portion of the mountain occupying the southwest corner of the ridgeline. A deep man-made lake, Round Valley Reservoir, occupies the valley at the center of the horseshoe.