Sediment anisotropy coincides with moraine ridge trend in south-central Finnish Lapland

The morpho‐sedimentary anisotropy of a field of moraine ridges, classified previously as ribbed moraine, was studied by means of ASTER satellite data, airborne radiometric (AR) data, digital elevation models (DEMs) and azimuthal measurement of electrical conductivity (σa) in Kivitaipale, south‐central Finnish Lapland. The 20 km long corridor of moraine ridges is diagonally oriented to the youngest (Late Weichselian) active‐ice streamlined features and presumably dates back to post‐Younger Dryas. The maximum σa anisotropy of sediments is parallel to the orientation of the ridge crests. Crudely to well stratified gravels and sands of glaciofluvial open channel origin and moderately sorted sediments attributed to glaciofluvial sliding bed facies are exposed in the cores of the ridges, whereas signs of (basal) till cover or glaciodynamic deformations are absent. On the basis of morpho‐sedimentary anisotropy, we contend that the origin of the studied corridor of ridges is linked to subglacial outburst event(s) rather than a transverse‐to‐ice‐flow origin of ribbed moraine. The triggering mechanism for the outburst(s) remains unresolved, yet the timing of outburst(s), concurrent with the maximum post‐Younger Dryas fault instability, may imply that earthquake(s) contributed to subglacial drainage.