Bixby State Preserve in southwestern Clayton County, Iowa, about three miles north of Edgewood, protects one of the state’s rare algific talus slope landscapes. In this unusual system of sinkholes, fissures, and ice caves, airflow reverses by season, drawing cold moist air onto north-facing slopes in winter and early spring and venting cool moist air there in summer and fall. That natural refrigeration sustains an ecosystem uncommon on a global scale. Managed by the Iowa Department of Natural Resources, the preserve has had limited access since June 7, 2013, after the only road in closed on both the north and south sides, though the south entrance opens during summer. Trout fishing is allowed.