The gorge is a typical antecedent valley, formed by the cutting of the Iskar River in the rising Stara Planina Range. About 4.5 million years ago, the Iskar River drained the lake that existed in the Sofia Field to the sea that occupied the Danube Plain at that time. During the cyclic erosional cutting of the river throughout the Quaternary, 6-7 terraces were formed, with the highest and oldest being 110-120 m above the river. Some of the terraces correlate with the exits of the numerous caves in the slopes. In the gorge, the Iskar River receives its tributaries Batuliyska Reka (right), Dalbochitsa (left), Iskretska Reka (left), Gabrovnitsa (right), Zlatitsa (left), etc. At the mouths of the rivers in the Paleozoic easily destructible rocks, the gorge widens.
North of Gara Bov it narrows and in places takes on the character of a gorge with a picturesque view – near the village of Lakatnik, the Cherepish Monastery and the village of Lyutibrod. The slopes of the gorge are heavily deforested, and the preserved vegetation has been anthropogenically altered. The forests are preserved in limited areas. Large areas of the slopes are occupied by former arable land and are subject to severe erosion. Screes and collapses often occur. At their mouths in Iskar, the side tributaries form alluvial cones.
Over 150 caves have been discovered in the Cherepish region. Most of them are insignificant in size and relatively poor in secondary cave formations. The longest is the Cherepish Cave, which is multi-storey, labyrinthine and has a total length of over 600m. Two of the caves in the region are protected – Serapionovata (protected area) and Novata (the New one) (natural landmark).
About 100 caves have been discovered in the Lakatnik region. Almost all are horizontal. Only about ten exceed 100m in length, but among them is Temnata dupka (the Dark Hole) (a natural landmark), which is one of the longest caves in the country.
