Lake Katharine State Nature Preserve is located in Jackson County, Ohio, United States, just northwest of and outside the city of Jackson. It is owned and administered by the State Division of Natural Areas and Preserves and comprises 2,019 acres (817 ha). The nature preserve is centered at Lake Katharine, an artificial lake. The valley is a small gorge, located in southerly extensions of the same geological series of rocks that forms the Hocking Hills Region. The bluffs are formed of weathering-resistant sandstone, including the blackhand sandstone.