This wildlife reserve is surrounded by three concentric ridges or rings of hills, which rise above the surrounding plains. It is named after a Tswana chief, Pilane. The "Pilanesberg Alkaline Ring Complex" is its main geological feature, this is ancient, even by geological standards, as it is the crater of a long-extinct volcano and the result of eruptions that occurred about 1.2 billion years ago. It is one of the largest volcanic complexes of its kind in the world, the rare rock types and formations make it a unique geological element. A number of rare minerals and several sites are found in the park indicating human activity dating back to the Iron Age and Stone Age. Because it is located in a transition zone, there is some overlap between the species of mammals, birds and vegetation that inhabit it. It is home to a rich variety of southern African flora and fauna, including the “Big Five”.