This 268-acre preserve protects one of the most spectacular dolomite and limestone gorges in the state. Registered as a National Natural Landmark in 1968, Clifton Gorge encompasses a 2-mile stretch of the Little Miami State and National Scenic River, just east of John Bryan State Park.

Geologically, it is an outstanding example of interglacial and post-glacial canyon cutting. At one point, the river funnels through a deep, narrow channel, which was apparently formed by the enlarging and connecting of a series of potholes in the resistant Silurian dolomite bedrock. In other sections of the gorge, cliff overhangs have broken off forming massive slump blocks scattered along the valley floor.

The shaded, north-facing slopes provide a cool, moist environment for northern species including hemlock, red baneberry, Canada yew, arbor-vitae and mountain maple. This is one of the most spectacular sites in the state for viewing spring wildflowers including the rare snow trillium.