Earthworm Activity: A Source of Potential Disturbance of Archaeological Sediments

Conspicuous disturbances in archaeological sites are readily detected during excavation. However, one animal whose destructive effects are not often recognized is the earthworm. Work at the Carlston Annis mound in Kentucky, an Archaic shell midden, has resulted in the identification of areas of extensive earthworm disturbance. Archaeological sites most readily affected are those with the appropriate vegetation cover, moisture and temperature conditions, and available chemical elements. The type of disturbance a site will undergo depends on the species of earthworms present. Subsurface-casting species mix matrix only below the surface while surface-casting species bring the fine-grained matrix to the surface, thus concentrating larger objects below ground. If earthworm casts are identified in a profile, one should proceed cautiously with interpretations concerning soil matrix.