loess

/ˈloʊəs/

Loess is a kind of fine dirt or dust that's made up of silt, sand, and clay. The wind blows loess around until it settles and, over time, accumulates in one area.

Where loess settles, the resulting soil tends to become very fertile, and to be distinctive for its yellowish-brown color. There are places rich in loess throughout the United States, as well as parts of China, Europe, and Argentina. There's even an area in Iowa called the "Loess Hills." The word loess is pronounced several ways, including "luss," and like the name Lois. It comes from the German Löss, "yellowish-gray soil."

Definitions of loess

1. noun

   a fine-grained unstratified accumulation of clay and silt deposited by the wind
   type of:

   dirt, soil

   the part of the earth's surface consisting of humus and disintegrated rock