喀斯特
The name of the dialect is somewhat misleading because its use is not limited to the Karst Plateau, nor does it encompass the entire Karst Plateau. It is spoken only in the northwestern parts of the Karst Plateau, in a line from the villages of Prosecco and Contovello near Trieste, west of Sgonico and Dutovlje. East of that line, the Inner Carniolan dialect is spoken. In addition to the northwestern part of the Karst Plateau, the dialect is spoken in the lower Vipava Valley (west of Črniče), in the lower Soča Valley (south of Ročinj), and on the Banjšice Plateau and the Trnovo Forest Plateau ().