Sudan copper, gold, granite, gypsum, iron, kaolin, lead, manganese, mica, natural gas, nickel, petroleum, silver, tin, uranium and zinc. The amount of rainfall increases towards the south. The central and the northern part have extremely dry desert areas such as the Nubian Desert to the northeast and the Bayuda Desert to the east; in the south there are swamps and rainforest. Sudan's rainy season lasts for about three months (July to September) in the north, and up to six months (June to November) in the south. The dry regions are plagued by sandstorms, known as haboob, which can completely block out
Sonoran Desert California; and the Yuma Desert east of the north-to-south section of the Colorado River in southwest Arizona. In the 1957 publication, "Vegetation of the Sonoran Desert", Forrest Shreve divided the Sonoran Desert into seven regions according to characteristic vegetation: Lower Colorado Valley, Arizona Upland, Plains of Sonora, Foothills of Sonora, Central Gulf Coast, Vizcaíno Region, and Magdalena Region. Many ecologists now consider Shreve's Vizcaíno and Magdalena regions, which lie on the western side of the Baja California Peninsula, to be a separate ecoregion, the Baja California Desert. Within the southern Sonoran Desert in Mexico is found the Gran Desierto de