Figure 11-5. McMurdo Station, Antarctica
Human alteration of landforms, relocation of soil for building of infrastructure, and alteration of soil profiles occur even in this remote location. (Photo by Alan Light)
Human-Altered Material
Human-altered material (HAM) is soil parent material (organic or mineral) that has undergone anthroturbation (mixing or disturbance by humans). It differs from HTM in that it generally has been altered in place and contains little or no evidence of being transported from another location. Examples include agricultural soils that have been deeply mixed (e.g., by deep ripping of a root-restrictive subsoil layer such as a duripan) and soils that have been mechanically compacted to impound water (as in a rice paddy with anthric saturation). The concept also includes soils that have been removed, stockpiled, and replaced during reclamation (as in some surface mining or urban development activities) and soil materials that remain exposed after excavation (such as those on the floor of a gravel pit).
Human-altered materials are commonly associated with destructional anthropogenic landforms. These landforms are in areas where soil material has been removed (pits, quarries, mined areas, etc.). In some cases, a destructional landform may be recognized by tracing a subsurface horizon (such as an argillic or spodic horizon) from adjacent non-human altered soils laterally to the point where it disappears abruptly, which corresponds to the boundary of the destructional landform. Destructional anthropogenic landforms are excavated but may later be filled or covered. Where the excavations have been partially or totally filled with the original soil material, the material is considered HAM.
Where they have been filled with different soil material, the material is considered HTM.
Evidence of human-altered material includes:
• Material occurs in an area impacted by the agricultural practices of deep plowing to rip a root-restrictve layer or of intentional compaction to puddle water.
• Material occurs within an excavated area (destructional landform) such as a pit or quarry.
• The soil profile has features such as reoriented pieces of diagnostic horizons; rock fragments that are mechanically abraded; scrape marks underlying soil material that was removed, stockpiled, and replaced on site; or purposely compacted layers formed during construction activities.
Figure 11-5. McMurdo Station, Antarctica
Human alteration of landforms, relocation of soil for building of infrastructure, and alteration of soil profiles occur even in this remote location. (Photo by Alan Light)
Human-Altered Material
Human-altered material (HAM) is soil parent material (organic or mineral) that has undergone anthroturbation (mixing or disturbance by humans). It differs from HTM in that it generally has been altered in place and contains little or no evidence of being transported from another location. Examples include agricultural soils that have been deeply mixed (e.g., by deep ripping of a root-restrictive subsoil layer such as a duripan) and soils that have been mechanically compacted to impound water (as in a rice paddy with anthric saturation). The concept also includes soils that have been removed, stockpiled, and replaced during reclamation (as in some surface mining or urban development activities) and soil materials that remain exposed after excavation (such as those on the floor of a gravel pit).
Human-altered materials are commonly associated with destructional anthropogenic landforms. These landforms are in areas where soil material has been removed (pits, quarries, mined areas, etc.). In some cases, a destructional landform may be recognized by tracing a subsurface horizon (such as an argillic or spodic horizon) from adjacent non-human altered soils laterally to the point where it disappears abruptly, which corresponds to the boundary of the destructional landform. Destructional anthropogenic landforms are excavated but may later be filled or covered. Where the excavations have been partially or totally filled with the original soil material, the material is considered HAM.
Where they have been filled with different soil material, the material is considered HTM.
Evidence of human-altered material includes:
• Material occurs in an area impacted by the agricultural practices of deep plowing to rip a root-restrictve layer or of intentional compaction to puddle water.
• Material occurs within an excavated area (destructional landform) such as a pit or quarry.
• The soil profile has features such as reoriented pieces of diagnostic horizons; rock fragments that are mechanically abraded; scrape marks underlying soil material that was removed, stockpiled, and replaced on site; or purposely compacted layers formed during construction activities.