A narrow strip of land along the north coast of Bahrain is irrigated by natural springs and artesian wells. South of the cultivable area, the land is barren. The landscape consists of low rolling hills with numerous rocky cliffs and wadis. From the shoreline the surface rises gradually toward the center, where it drops into a basin surrounded by steep cliffs. Toward the center of the basin is Jabal ad-Dukhan, a rocky, steep-sided hill that rises to 122 m (400 ft). Most of the lesser islands are flat and sandy, while Nabih Salih is covered with date groves.