The Sudetes are old mountains, with rocks from the oldest geological periods. The landscape of the Sudetes is characterized by contrasts between the gentle surfaces of the ridges and the deeply carved valleys of mountain rivers with steep slopes and numerous waterfalls. The peculiarity is the numerous forms of rock weathering in the form of rock debris or picturesque groups in the ridge parts. The Sudetes are divided into the Western Sudetes, Middle, and Eastern.