Orientationsstruktur der Talanlagen in der Schweiz

Abstract. The orientation of the Valleys in Switzerland shows a remarkable symmetry. It is the aim of this paper to represent this symmetry in numerical terms and to seek a physical cause thereof. For this purpose, the valley directions have been «rectified» (i. e. straightened) by considering them as edges in a graph. In this fashion, the distribution of orientations can be represented numerically and, in consequence, can be analyzed statistically. It is shown that the preferred orientations are ENE and SSE, which is the same as the preferred orientations of the strikes of the rock-joints in the region. Inasmuch as the joints are thought to be caused by the neotectonic stress field, the coincidence of the orientations of joints and river valleys is a strong indication that the latter are determined by the same neotectonic stress field as well. Data from fault plane solutions of earthquakes support this contention.