The topography of Yemen features a narrow coastal plain backed by flat-topped hills and rugged mountains. Dissected upland desert plains in the center of the country slope into the desert interior of the Arabian Peninsula. The highest known point is the summit of Jabal Hadhur, rising 3,760 m (12,336 ft) above the Red Sea coast. The western part of the country contains fertile soil in its highland plateaus which rise from about 1,200 to 3,000 m (4,000 to 10,000 ft). Approximately 3% of Yemen's land is arable. A system of wadis drain mountain slopes into the desert and into the Gulf of Aden.