An extremely fertile, yellowish, fine loamy soil of wind-deposited silt, often composed of the following mineral components: quartz, feldspar, horneblende, mica, and clay minerals. The silt is blown in from dry, arid places and have glacial origins. Thick deposits of loess are found on the east side of the Mississippi and Illinois rivers, and hill prairies occur on some of these deposits. The loess carried down from the highlands north of the Tibetan plateau to the North China Plain by the Yellow River (so named because of its color due to the loess) played an important role in the development of ancient Chinese civilization.