Longitudinal valley

Many longitudinal valleys follow the strike of the rock strata or significant geological fault lines.

The faults are structures that reach deep into the lower part of the Earth's crust, which is already in place before the actual mountain building phase and is later reactivated.

In such cases, longitudinal valleys generally run along the so-called leading edge of the nappe (the overthrust front) and are oriented at right angles to the direction of movement of the tectonic nappes, which in turn correspond to the direction of movement of the colliding continental blocks.

Particularly long valley systems that are occupied by several rivers, sometimes running in opposite directions, are known in German as Längstalfurchen ("longitudinal troughs"), as opposed to the usual Längstäler, although no such distinction is made in English.

The Eastern Alps and other Alpine ranges have many such troughs, which are almost straight for a distance of several hundred miles and were accentuated by glacial processes during the Pleistocene.