ZAGROS MOUNTAINS

mountain range in southwestern Iran, extending northwest-southeast from the Sirvan (Diyala) River to Shiraz. The Zagros range is about 550 miles (900 km) long and more than 150 miles (240 km) wide. Formed primarily of limestone and shale, the mountain range consists of numerous parallel ridges whose highest peaks rise above 12,000 feet (3,600 m) and have permanent snow cover. Passes through the mountains are used for reaching the fertile intermontane plains, which lie at elevations of more than 5,000 feet (1,525 m). The rivers draining the range's western face are strong and perennial, flowing through enclosed plains or ravines. Rainfall in the region is about 40 inches (1,000 mm) annually.