Rohan lies to the north of the Ered Nimrais, and its great plans are covered by tall grasslands typically  found on the leeward side of great mountain ranges. These grassy plains roll gently westward from the Mering Stream, towards the near shore of the River Isen, and northward towards the eaves of Fangorn. These rich grasslands are bisected by the broad, flat valley of the Entwash River, where a wide swathe of meads, pastures, fens and marshlands prevail. On the eastern side of the Entwash, the rolling plains resume until they meet Rohan's Eastern Wall (the rocky terrain of the Emyn Muil) and northern highlands of the Downs and Wold. The terrain of the Emyn Muil consist predominately of tree and scrublands, whilst the Downs and Wold are covered with sparser pastures and grazing. Dense forests occur around the confluence of the Snowbourne and River Entwash, and along the Mering Stream (The Firien Wood) on Rohan's eastern border with Gondor. A section of the Westfold and West-march, south of the Great West Road and west of the White Mountains, is covered by woodland.