mountain belts
Intermediate structural level: Hinterland, Recumbent folds, thrust and nappes
In the intermediate and deeper structural level, structures and fabrics are the result of a combination of tectonic and gravity forces. On the example presented here, the regional structure is the result of the combination between: three gravity driven mechanism.
Gravitational spreading: The spreading occurs along a flat basal surface. Motion is driven by the slope of the surface topography.
Gravitational sliding: The basal surface and the surface topography are dipping in the same direction. Along with gravitational spreading, ductile gliding occurs along the basal surface.
Ductile extrusion: spreading is driven by the intense shortening of the basement.

In the intermediate structural level, the strain is pervasive. The finite strain field is characterized by moderately to shallow dipping finite flattening planes and stretching lineations. In contrast to the upper structural level, the finite flattening plane does not systematically face the hintherland. In maps, thrust faults and foliation trajectories have contorted contours due to their shallow dip. Strain changes in both orientation and intensity in the vicinity of nappe contacts. The obliquity between the finite flattening plane and the thrust plane is indicative of the kinematic of the fault. The stretching lineations in the vicinity of the thrust faults have a coherent orientation parallel to the direction of the tectonic transport. In the pile, in particular in the front of the nappes, the direction of transport may be controled by gravity and therefore stretching lineations may have various direction.