The northern deformation front of the European Alps, i.e. the northern limit of Alpine thrusting, is characterized by structural variability along strike. It can be subdivided into four regions: the deformation front in (i) France and Switzerland, (ii) western Austria and Bavaria, (iii) eastern Bavaria, Salzburg and Upper Austria, and (iv) Lower Austria. In France and Switzerland, the deformation front can be subdivided into the external Jura Mountains, the Plateau Molasse and the Subalpine Molasse, i.e. the part of the foreland that has been included into the orogenic wedge after deposition. The deformation front in France and Switzerland is directly linked to the basal décollement below the External Crystalline Massifs. The external position of the Jura fold-thrust belt is associated with the occurrence of Triassic salt deposits in the European margin sediments. The Subalpine Molasse can be considered the frontal-most part of the Helvetic thrust sheets. South of the Jura fold-thrust belt it is characterized by a continuous triangle zone extending from Lake Geneva to SW of Munich. South of Lake Constance lies the transition between Central and Eastern Alps. While this transition is pronounced within the Alpine orogen, it is less evident at the deformation front. East of Lake Constance, structural styles as well as mechanical stratigraphy are comparable to observations in Switzerland and France. Further to the east however, the Subalpine Molasse tapers off and completely disappears east of Munich. This coincides with a gradual change of structures exposed that the surface, because deeper sections of the Subalpine Molasse are exposed in the west. East of Munich in eastern Bavaria, Salzburg and Upper Austria, location of the basal décollement of the deformation front varies between Cretaceous and Rupelian units. No frontal triangle zone developed; instead duplexes buried by foreland deposits dominate the structural style. On the eastern side of the Bohemian Spur there is a marked change in the strike of the Alpine deformation front, paralleling pre-existing geometries of the underlying European Basement units. This is also reflected in the structural styles and timing of thrusting along the deformation front.
This large variability of the geometries of the Alps northern deformation front is associated with the variable mechanical stratigraphy along strike, the different links to more internal units of the Alps, as well as links to the deep structure of the Alps, in particular the geometry and overall mechanical properties of the down-going European Plate. Similar to different geometries, timing and sequence of thrusting of the deformation front is highly variable along strike. This difference is caused by a link of the deformation front to the deep and shallow dynamics of the Alps. This stresses the need for a comprehensive approach to resolve the dynamics of the deformation front, including sedimentological and structural studies from outcrop to mountain belt scale. At the same time, the complexity of the deformation front is a unique record of the dynamics of the orogen through time.