The Marzuq Desert is located in the southwestern corner of Libya and is made up of the Idehan Marzuq (sandy desert) and the Hammadat Marzuq (rocky desert). The Idehan Marzuq, visible in the eastern third of this photograph, covers approximately 36 000 square miles (58 000 square kilometers). This sandy desert has two types of sand dunes—linear dunes to the south-southeast and crescentric, compound dunes to the west-northwest. Most of the reddish eolian sand in the Marzuq Desert was transported from the volcanic area of the highland region in the northeast, principally from sources lying northeastward toward the Gulf of Sidra and northeast Libya. The Hammadat Marzuq (rocky desert), with eroded, darker bedrock outcrops (aligned north-south), lies west and northwest of the sandy desert. Several wadis (watercourses or dry riverbeds) are visible in the bedrock outcrops. The western half of the photograph is a mixture of exposed bedrock outcrops (dark surfaces) and an assortment of sand dunes. The dark, small, rectangular-shaped area near the northeastern corner of the Idehan Marzuq is a series of circular (center-pivot) irrigation plots that are used to grow crops in the Libyan desert.