Catfish Creek Preserve is located in the north half of the 1,300-acre Mines of Spain Recreation Area, on the south side of the city of Dubuque, in Dubuque County. The preserve contains unique historic sites related to the first European settlement of Iowa and geological landforms illustrating stream piracy. The Mines of Spain Recreation Area was purchased by the Iowa Natural Heritage Foundation and later transferred to the Iowa Conservation Commission in 1980. In 1991, approximately 600 acres in the northern half of the recreation area were dedicated as a geological, archaeological, and historical state preserve. Geologically, the preserve lies within the southern portion of the Paleozoic Plateau landform region. Many characteristics of the Paleozoic Plateau can be found here, including scenic rock outcrops of Ordovician (450 million years old) Galena dolomite, high bluffs, narrow ridges, deeply dissected streams and ravines, seeps, caves, and vertical crevices. The Mississippi River floodplain borders the entire eastern boundary with its entrenched 200-foot bluffs. Catfish Creek (after which the preserve is named) and Granger Creek flow through narrow valleys in the northern section of the preserve. The valleys were altered or abandoned when the Mississippi River, fed by massive glacial meltwater flows, further cut into the bedrock, leaving these good examples of “stream piracy.” Two sections of abandoned valley associated with the former course of Catfish Creek are north of the present-day stream valleys and in the Horseshoe Bluff area.