Superposed minor structures

Abstract

These words, written by de Margerie and Heim in 1888 (p. 61) are equally applicable to this section. In the Alps, and other young mountain ranges, the complexities of refolding can commonly be seen in the great natural cross sections formed by the mountain cliffs. Elsewhere, in the older orogenic zones, much of the structure can only be seen in two dimensions, and the third has to be deduced from surface evidence. This may be greatly facilitated if one appreciates that each successive movement will not only modify the pre-existing structures, but at the same time is liable to produce its own minor structures. If, therefore, we observe that one set of minor structures regularly deforms another we have an indication that more than one movement has taken place. Then, if we can link these minor structures with their respective major structures, we will have taken a long step in the elucidation of the tectonic history of our area.

Un cas remarquable est encore à considérer, c’est celui qui se produit lorsqu’un pli est lui-même replié, soit lors d’une nouvelle période de plissement, soit directement dans la même période. *