Near the two major rivers (Euphrates and Tigris) are fertile alluvial plains, as the rivers carry about  of silt annually to the delta. Rocky deserts cover about 40 percent of the land. Much of the south is marshy and damp.  Another 30 percent is mountainous with bitterly cold winters. The north of the country is mostly composed of mountains; the highest point being at  point, unnamed on the map opposite, but known locally as Cheekah Dar (black tent). Iraq has a small coastline measuring  along the Persian Gulf. Close to the coast and along the Shatt al-Arab (known as ''arvandrūd'': اروندرود among Iranians) there used to be marshlands, but many were drained in the 1990s.