Relief of all areas is a result of its morphogenesis, the result of the action of endogenous and exogenous geomorphological processes. Kozara Mountain belongs to the category of island mountains, whose basic, tectonic relief was formed during the period of Cainozoic by lifting a part of the land by the orogenic movements of the Earth’s crust and by the draining of the Pannonian Sea. The most important period of the Kozara massif tectonic formation is the period of Alpine orogenesis in the end of Mesozoic and the beginning of Eocene.
The highest peaks rose from the Pannonian Sea during the older Tertiary (Eocene). Kozara was originally an island, and after the draining of the Pannonian Sea Paratethys, it became a part of the mainland. Exogenous forces and the destructive power of erosion moulded the relief furthermore.
The relief image of Kozara Mountain is characterized by several interconnected ridges, mountain slopes, isolated peaks and deeply incised stream valleys. Although the highest peaks of Kozara Mountain do not exceed the altitude of 1000 m, it can be said that the main characteristic of this mountain is the highly expressive relief.
The relief of the Kozara National Park is very expressive and it influences the climate conditions and vegetation of this region. Different relief forms typical for geological substratum of this area are present: mountain peaks, reefs, plateaus, slopes, valleys, ravines, sinkholes, hills, etc. Long slopes steeply descending into the stream valleys were formed on the Cretaceous-Eocene flysch. Gabrodolerits and serpentines form short and steep slopes. Typical karst features (ridges, valleys and basins) are typical for limestone areas (Kozarački and Zečiji kamen, Sokoline, Vrnovačka glava, Jankovica, Starenica valley, Gola planina Mountain). Monotonous steep slopes developed on marly limestone and marls. On the border between the substrate and gabrodolerits, the relief suddenly turns into gorges or beams. The most prominent anticlines are in the central part: Gola planina Mountain (874 m) and Mrakovica (806 m). Other significant heights are: Vinogreč (816 m), Glavuša (793 m), Cerik (745 m), Jarčević (736 m), Kriva strana (723 m), Slatinska glava (710 m), Jankovica (685 m), Razboj (676 m), Bukovi vrh (667 m), Kozarački kamen (659 m), Šupikovac (652 m) Hrastova glava (574 m). From the main anticline on the line Gola planina Mountain - Mrakovica - Glavuša ornated series of slopes descend towards the northern and southern foot of the mountain. Significant slopes are: Vitlovska slope, Šibovac, Babina, Tisova and Stevanova slope, Mijakov klin, etc. The stream valleys between the slopes on the upper part of the flow are very tight, and their slopes are very steep (30-40%), especially in the southern part of the area where the vertical dissection of the terrain is very prominent. Wide, relatively flattened plateaus of Mrakovica, Gola planina and Bešića poljane stand out in the highest zone, and Pašini konaci, a broad and shallow depression, at the northern edge of the area stands in the lower zone of the area.
The general feature of the relief of the Kozara National Park is great dynamic of the relief with carved valleys, mountain slopes, ridges and isolated peaks.