The IBA consists of two main landscape features: Tupižnica mountain (1.162 m) and Beli Timok river. Tupižnica is situated northwest of Knjaževac valley and southwest of Zajecar valley in Eastern Serbia and is a prominent mountain, surrounded by numerous valleys whose watercourses flow into Beli Timok. It mostly consists of a large karst plateau. It is remote and uninhabited, especially its vast forested northern parts, towards villages of Gornja Bela Reka and Lenovac in Zaječar municipality. It is rich with numerous forms of karst relief, such as caves, karst pits and sinkholes. The valley along the river Beli Timok is very heterogeneous and represents a mosaic of arable land, forest groves, meadows and orchards, especially to west, towards Tupižnica mountain.