Alikerros

Alikerros is a Finnish term used in geology and soil science to denote a lower layer within a stratified sequence. The word combines ali- meaning sub- with kerros meaning layer. It is typically employed as a practical, non-technical descriptor for one or more deeper layers beneath the surface horizons of a soil or sediment sequence, rather than a formal horizon name.

In soil profiles, alikerros commonly refers to the subsoil, including the B horizon and, when present, deeper C horizons. Characteristics usually differ from surface horizons: lower organic matter, higher mineral content, greater density, less biotic activity, and effects from leaching or illuviation, depending on climate and parent material. The exact composition and thickness of an alikerros vary widely by location.

In geology and archaeology, the term is used in field notes to describe lower sedimentary deposits or stratigraphic units in a site, helping to interpret formation processes or occupation history. In civil engineering, the properties of the alikerros influence groundwater behavior, bearing capacity, and foundations, so it is commonly assessed in geotechnical surveys.

Because alikerros is a general concept, it is used alongside more precise horizon names such as the B horizon, C horizon, or bedrock, depending on context and classification system. Related terms include subsoil, soil horizon, bedrock, stratigraphy, and sedimentology.