Johnson Run Natural Area is a 216-acre (87 ha) nature preserve located in Cameron County, Pennsylvania. The topography consists of a rugged, bouldered plateau dissected by steep-sided streams and covered with somewhere from 26 acres (11 ha) to 50 acres (20 ha) of old-growth forest containing Eastern Hemlock and Eastern White Pine. Some of the white pines are nearly 4 feet (120 cm) in diameter at breast height.