1) Symbol of South Dakota 
[soil] Houdek is a type of soil composed of glacial till and decomposed organic matter. It is found only in the U.S. state of South Dakota where it is the state soil. Houdek topsoil is composed of weathered glacial till and 2% to 4% organic matter which gives it a deep, dark color. The subsoil consists of layers of clay and lime accumulatio...