From Carcassonne, the river becomes calmer following the great tectonic furrow which separates the Pyrénées (Corbières) from the Massif Central (Montagne Noire), receiving from these heights a series of tributaries of which the main ones are the Orbieu on the right bank, and the "Argent-Double" and the "Casse" on the left bank. From this point, bordered by the Canal du Midi and sinuous amid vineyards, the Aude enters the broad alluvial plain of Narbonne with the main stream flowing to the Gulf of Lion and some waters diverted to a network of ancient ponds before flowing into the Mediterranean Sea .