The largest valley in Jordan, Wadi Rum, Valley of the Moon, is a valley cutting through sandstone and granite. It is believed to get its name from a lost city mentioned in the Quran. Wadi Rum is characterized by tall, near vertical mountains of iron-rich, erosion resistant, Umm Ishrin Sandstone, separated by flat-bottom valleys of alluvial sediments, aeolian sands, and salt pans. Narrow canyons and fissures cut deep into the mountains and many conceal ancient rock drawings etched by the peoples of the desert over millennia. Wadi Rum has been inhabited by many human cultures since prehistoric times, with many cultures leaving their mark in the form of petroglyphs, inscriptions, and temple ruins.