Rock of Gibraltar may have originated from an escape of North African animals transported to Spain; it is also possible that the original Gibraltar macaques are a remnant of populations that are known to have spread throughout Southern Europe during the Pliocene, up to 5.5 million years ago. Some animals of the Rock have been reintroduced by the Alameda Wildlife Conservation Park who have three Barbary macaques. The Rock of Gibraltar, at the head of the Strait, is a prominent headland, which accumulates migrating birds during the passage periods. The vegetation on the Rock, unique in southern Iberia, provides a temporary home for
Gibraltar Rock State Natural Area a major tourist draw. The track for the area does not have wheelchair access. People are not allowed to climb the rocks in the park, though this has not always been the case. The natural area is located on the outer part of the Magnesian Escarpment/Black River Escarpment, with the soil for the area being glaciated sandy loams, which sit on top of the Galena-Platteville dolomite cap and St. Peter sandstone. Inside the natural area is a flat-topped butte called "Gibraltar Rock." It sits above sea level and is the highest point in Columbia Country. There is a trail leading