The Pannonian Basin took shape through Miocenian thinning and subsidence of crust structures formed during Late Paleozoic Variscan orogeny. The Paleozoic and Mesozoic structures are visible in Papuk and other Slavonian mountains. The processes also led to formation of a stratovolcanic chain in the basin 17 - 12 Mya and intensified subsidence observed until 5 Mya as well as flood basalts about 7.5 Mya. Contemporary uplift of the Carpathian Mountains severed water flow to the Black Sea and Pannonian Sea formed in the basin. Sediment were transported to the basin from uplifting Carpathian and Dinaric mountains, with particularly deep fluvial sediments being deposited in the Pleistocene during uplift of the Transdanubian Mountains. Ultimately, up to of the sediment was deposited in the basin, and the sea eventually drained through the Iron Gate gorge.