Persisteringslag

Persisteringslag is a term used in Norwegian geology and soil science to describe a stratigraphic layer characterized by persistent properties that influence processes over long timescales. It denotes a distinct horizon where physical or chemical characteristics, such as low permeability, mineralogy, or moisture retention, remain comparatively stable relative to surrounding materials.

It forms when diagenetic, sedimentary, or soil-forming processes create a durable boundary—often a clay seam, cemented zone, or mineralogical change—that reduces flow or diffusion. The layer may range from centimeters to meters in thickness and is identified through core sampling, borehole logs, and geophysical or geochemical analyses, which reveal contrasts in porosity, permeability, or tracers.

Persisteringslag affects groundwater movement, contaminant transport, and thermal-moisture regimes within a basin. It can preserve palaeoclimate signals and alter engineering conditions for foundations, tunnels, and excavations due to its differing mechanical properties.

The term is predominantly used in Norwegian-language literature, though its exact scope can vary. In international contexts, similar concepts include aquitards, cap rocks, or persistent clay layers.