rygglager

Rygglager is a term used in geology and stratigraphy, particularly in Swedish-language literature, for a sedimentary layer associated with ridge topography. The word combines rygg (ridge) and lager (layer). The concept describes how deposition occurs preferentially along crests and slopes of ridges, producing a definable stratigraphic unit that records sediment transport and energy conditions across elevated terrain.

Formation and characteristics: Rygglager layers often display alignment parallel to ridge crests and can be cross-bedded, ripple-laminated, or planar laminated depending on the depositional environment. Thickness varies with relief, relief-driven sediment supply, and subsurface processes. Diagenetic features such as cementation or compaction may be present. In aeolian settings, rygglager may form crest or dune-front deposits; in fluvial or coastal settings, they reflect high-energy conditions along ridges.

Occurrence: While the term is rooted in Nordic geological literature, the underlying phenomenon is observed in sedimentary sequences worldwide where ridge topography influences sediment deposition and stratigraphic architecture.

Study and interpretation: Field mapping and stratigraphic correlation delineate rygglager units. Facies analysis, grain-size distributions, and paleocurrent indicators help interpret depositional environments, transport directions, and past topography. Rygglager can aid reconstructions of paleogeography in regions with pronounced ridge systems.

See also: stratigraphy, sedimentology, cross-bedding, paleocurrent analysis.