Andisols are soils that typically form in loose volcanic ejecta (tephra) such as volcanic ash, cinders, or pumice. They are characterized by andic properties that include physical, chemical, and mineralogical properties that are fundamentally different from those of soils of other orders. These differences resulted in a proposal to recognize these soils at the highest level in the USDA soil classification system (Smith, 1978). In 1990, Andisols were added to Soil Taxonomy as the 11th soil order (Soil Survey Staff 1990; Parfitt and Clayden, 1991). A very similar taxonomic grouping, Andosols, is one of the 32 soil reference groups recognized in the World Reference Base for Soil Resources (IUSS Working Group, 2006). Andisols (and Andosols) are classified on the basis of selected chemical, physical, and mineralogical properties acquired through weathering and not on parent material alone. Both soil names relate to two Japanese words, anshokudo meaning “dark colored soil” (an, dark; shoku, color or tint; do, soil) and ando meaning “dark soil”. Ando was adopted into western soil science literature in 1947 (Simonson, 1979).