The mountains were created during the Alpine Orogeny in the Cenozoic. Geologically, they consist mainly of flysch deposits. In the north, they steeply rise nearly over a rather flat landscape; in the south, they slowly merge with the Javorníky. In the south-west, they are separated from the Vsetínské vrchy by the Rožnovská Bečva valley; in the north-east, the Jablunkov Pass separates them from the Silesian Beskids.