The windblown silt that blankets landscapes is called loess. Loess is a fine-grained, yellowish-brown sediment composed primarily of silt-sized particles (between 0.05 and 0.002 millimeters in diameter) that has been deposited by the wind. Loess deposits are typically found in areas that are downwind of large, arid regions, such as the Sahara Desert in Africa and the Gobi Desert in Asia. Loess is a very fertile soil, and it is used to grow a variety of crops, including wheat, corn, and soybeans.