Eastern Carpathians

stretching from the N-NW border of the country down to the Prahova Valley, are made up of volcanic rocks, Mezozoical-crystalline rocks and flysch, the highest elevation being of 2,303 m (the Pietrosu Peak in the Rodna Mountains); their inner rim is formed of the longest chain of volcanic mountains in Europe (the Oas, Gutii, Tibles, Calimani, Gurghiu, Harghita, Bodoc, Baraolt mountains);

Southern Carpathians

standing between the Prahova Valley and the Timis-Cerna and Bistra corridors, which are made chiefly of crystalline schists and are the country's highest (maximum elevation 2,544 m, the Moldoveanu Peak in the Fagaras mountains; other massifs with elevations exceeding 2,500 m are: Negoiu - 2,535 m, Paringu Mare - 2,519 m, Peleaga - 2,509 m, Omu - 2,505 m a.s.o.);

Western Carpathians

situated in the west of the country, between the Danube to the south and the Somes river to the north, consists of a mosaic of rocks (sedimentary, eruptive, crystalline) and have karstic zones; their height is reduced (maximum elevation 1,849 m, the Curcubata Mare Peak in the Bihor Mountains).