 Požeška gora, adjacent to Psunj, consists of much more recent Neogene rocks, but there are also Upper Cretaceous sediments and igneous rocks forming the main, ridge of the hill; these represent the largest igneous landform in Croatia.A smaller piece of igneous terrain is also present on Papuk, near Voćin.The two, as well as the Moslavačka gora mountains, are possibly remnants of a volcanic arc from the same tectonic plate collision that caused the Dinaric Alps.