Cuestas in Gutland (S Luxembourg) and Belgian Lorraine: Evolution of a Structurally Controlled Landscape

Abstract

The cuesta landscape of Belgian Lorraine and Luxembourg’s Gutland belongs to the north-eastern rim of the Paris Basin, characterized by the wide syncline of the Gulf of Luxembourg. Highlighting the underlying geological structure and lithology, the cuestas were progressively sculpted in close relation with the contrasted evolutions of the Meuse and Rhine river systems. The landscape was established during the Cenozoic in Triassic and Jurassic rocks. These are formed of alternating hard pervious and soft, generally impervious units, the latter with a limited resistance to superficial weathering under the climatic conditions of the Neogene and Quaternary. The hard units frequently appear as thick homogenous layers, not only making the core of the cuestas but featuring also many escarpments. Height and lateral extent of the cuestas are controlled by the thickness of the hard layers and lateral changes in facies, as exemplified in the Middle Liassic sandstone and Triassic rocks. Remnants of an extended Neogene erosional surface cut the cuesta summits at ~400–420 m asl. Later fluvial erosion incised this surface, allowing for the development of lower planation surfaces down to 300 m, including a prominent level at ~350 m. Lower structural surfaces also exist on top of hard layers. Finally, landsliding is shown to participate actively in sculpting the cuesta landscape.