kryssbedding

Kryssbedding, or cross-bedding, is a sedimentary structure characterized by inclined internal layers that dip within a largely horizontal rock bed. It forms when sediment is deposited on migrating bedforms such as sand dunes, ripples, or bars, causing displaced layers to accumulate at an angle to the base layer.

In aeolian environments, wind-driven dunes and dune trains create trough cross-bedding, where inclined foresets record the direction and strength of the wind. In subaqueous settings, migrating underwater dunes, bars, or ripples produced by moving water form similar inclined sets. Cross-bedding typically consists of stacked cross-bed sets, bounded by truncation surfaces, and the individual foresets can vary in thickness and dip angle. Dip angles commonly range from roughly 10° to 40°, with steeper angles for large dunes.

The primary diagnostic value of kryssbedding lies in its ability to reveal ancient flow directions and depositional environments. By measuring cross-bed orientations, geologists infer palaeocurrents and paleowind regimes. The sedimentary environment—desert dunes, braided rivers, deltas, or continental shelves—can often be distinguished from the geometry and lateral context of the cross-beds. Cross-bedded units also influence rock properties, as the internal dipping layers create anisotropy in porosity and permeability, which is of interest in hydrocarbon reservoir studies.

Kryssbedding is commonly observed in sandstones and related lithologies preserved in outcrops and subsurface cores. Its recognition aids reconstructing ancient landscapes, sediment transport, and climate conditions.