Tongues (Figure 116).
Tongues are lobe-shaped extensions of a horizon penetrating downward into the adjacent underlying horizon. Examples include penetrations of an albic horizon into an argillic or spodic horizon, a mollic epipedon into a cambic horizon, and a calcic horizon into the underlying C horizon. Although tongues are commonly described in soil profile descriptions for penetrations that are deeper than their width, there is no formal definition of what constitutes a tongue. The first edition of Soil Taxonomy included a diagnostic feature for a specific kind of tongue, i.e., tonguing of albic materials, that had a definition specifying width that varied by texture. This diagnostic featured was later dropped (Keys to Soil Taxonomy, 5th edition, 1992); that specific kind of tongue was included within the definition of interfingering of albic materials. Horizons that have more than just a few tongues are commonly described with an irregular topography class for the lower boundary.
Figure 116.—Examples of tongues of a horizon that penetrate downward into an underlying horizon.
Left photo: Fox soil (Typic Hapludalfs). The Fox series consists of very deep, well drained soils, moderately deep to stratified calcareous sandy outwash. These soils formed in thin loess and in loamy alluvium overlying stratified calcareous sandy outwash.
Middle soil: OreliaOrelia soil (Typic Argiustolls). The Orelia series consists of very deep, well drained, slowly permeable soils that formed in loamy fluviomarine deposits of Pleistocene age.
Right photo: SanoSano soil (Glossic Fragiudults). The Sano series consists of very deep, moderately well drained soils with a fragipan in the subsoil. The soil formed in a silty mantle 40 to 70 inches thick and the underlying residuum weathered from limestone or siltstone.
Tongues (Figure 116).
Tongues are lobe-shaped extensions of a horizon penetrating downward into the adjacent underlying horizon. Examples include penetrations of an albic horizon into an argillic or spodic horizon, a mollic epipedon into a cambic horizon, and a calcic horizon into the underlying C horizon. Although tongues are commonly described in soil profile descriptions for penetrations that are deeper than their width, there is no formal definition of what constitutes a tongue. The first edition of Soil Taxonomy included a diagnostic feature for a specific kind of tongue, i.e., tonguing of albic materials, that had a definition specifying width that varied by texture. This diagnostic featured was later dropped (Keys to Soil Taxonomy, 5th edition, 1992); that specific kind of tongue was included within the definition of interfingering of albic materials. Horizons that have more than just a few tongues are commonly described with an irregular topography class for the lower boundary.
Figure 116.—Examples of tongues of a horizon that penetrate downward into an underlying horizon.
Left photo: Fox soil (Typic Hapludalfs). The Fox series consists of very deep, well drained soils, moderately deep to stratified calcareous sandy outwash. These soils formed in thin loess and in loamy alluvium overlying stratified calcareous sandy outwash.
Middle soil: OreliaOrelia soil (Typic Argiustolls). The Orelia series consists of very deep, well drained, slowly permeable soils that formed in loamy fluviomarine deposits of Pleistocene age.
Right photo: SanoSano soil (Glossic Fragiudults). The Sano series consists of very deep, moderately well drained soils with a fragipan in the subsoil. The soil formed in a silty mantle 40 to 70 inches thick and the underlying residuum weathered from limestone or siltstone.