desert in northeastern Sudan. It is separated from the Libyan Desert by the Nile River valley to the west, while to the north is Egypt; eastward, the Red Sea; and southward, the Nile again. Unlike the Libyan Desert, the Nubian Desert is rocky and rugged, though there are some dunes, and toward the Red Sea the desert, rising in gentle slopes to the west, culminates in precipitous uplands of the Red Sea Hills (Jabal Erba 7,273 feet 【2,217 m】) to the east. It is essentially a sandstone plateau interspersed with many wadis (seasonal rivers) that die out before reaching the Nile. The rainfall averages less than 5 inches (125 mm) a year.