Rock structure (Figure 95).
Rock structure.—A characteristic of unconsolidated soil materials in which the fine stratifications of sediments (alluvial, eolian, lacustrine, or marine), or the minerals or pseudomorphs of saprolite inherited from bedrock parent material, retain their original relative positions. The prevalence of rock structure that persists in the soil material is an indication that little pedogenic development has occurred. The lack of rock structure throughout most of a layer is a diagnostic criterion included in many of the definitions of diagnostic epipedons and subsurface horizons in the Keys to Soil Taxonomy.
Figure 95.—Examples of unconsolidated soil materials in which the fine stratifications of sediments (alluvial, eolian, lacustrine, and marine) remain.
Left photo: Alluvial Sediments—Trail soil (sandy, mixed, mesic Typic Torrifluvents). The Trail series consists of very deep, well drained and somewhat excessively drained soils that formed in stratified alluvium. Trail soils are on floodplains and alluvial fans.
Middel photo: Aeolian Sediments—Soil profile with rock structure as fine to coarse stratifications throughout. The upper 60 cm is recent eolian sand. The lower part consists of old alluvial deposits interspersed with eolian strata. The soil is a Torriorthent in the United Arab Emirates.
Right photo: Lacustrine sediments—Soil profile of an Entisol (lacustrine lake bed sediment) from China. (Photo provided by China Soils Museum, Guangdong Institute of World Soil Resources, Guangdong, China.)
Rock structure (Figure 95).
Rock structure.—A characteristic of unconsolidated soil materials in which the fine stratifications of sediments (alluvial, eolian, lacustrine, or marine), or the minerals or pseudomorphs of saprolite inherited from bedrock parent material, retain their original relative positions. The prevalence of rock structure that persists in the soil material is an indication that little pedogenic development has occurred. The lack of rock structure throughout most of a layer is a diagnostic criterion included in many of the definitions of diagnostic epipedons and subsurface horizons in the Keys to Soil Taxonomy.
Figure 95.—Examples of unconsolidated soil materials in which the fine stratifications of sediments (alluvial, eolian, lacustrine, and marine) remain.
Left photo: Alluvial Sediments—Trail soil (sandy, mixed, mesic Typic Torrifluvents). The Trail series consists of very deep, well drained and somewhat excessively drained soils that formed in stratified alluvium. Trail soils are on floodplains and alluvial fans.
Middel photo: Aeolian Sediments—Soil profile with rock structure as fine to coarse stratifications throughout. The upper 60 cm is recent eolian sand. The lower part consists of old alluvial deposits interspersed with eolian strata. The soil is a Torriorthent in the United Arab Emirates.
Right photo: Lacustrine sediments—Soil profile of an Entisol (lacustrine lake bed sediment) from China. (Photo provided by China Soils Museum, Guangdong Institute of World Soil Resources, Guangdong, China.)