Swiss contributions to mid-nineteenth century tectonic research: a step backwards or the prologue to the nappe tectonics revolution?

Abstract

AbstractTectonic research in the Swiss Alps between 1850 and the acceptance of tectonic nappes around 1900 is often reported as a rather conservative era, with much new data (mapping and stratigraphic), but very few new ideas. This paper challenges this view by proposing that Arnold Escher, a professor at Zurich University, arrived at a fundamentally new view of looking at Alpine tectonics around 1853. Whereas traditional continental European models of orogenesis assumed the vertical uplift of magmatic rocks with only minor and local crustal contraction, Escher's new model implied a net horizontal contraction of the Earth's crust across the Alps. With this proposal Escher was in agreement with the increasingly important theory of French and Anglo-Saxon geologists about the contraction of the Earth, but he broke with the traditions of his colleagues in the German-speaking community. His pupils Albert Heim and Armin Baltzer developed Escher's ideas further and helped to establish ideas about the mechanical deformation of rocks, while disproving older and not very well founded ideas about metamorphism being the main driver of orogeny. Unfortunately, Heim's later stubborn insistence on a specific detail of this new tectonic model – the famous Glarus Double Fold – delayed the acceptance of the idea of nappe tectonics, even though nappes would otherwise have fitted very well into the tectonic model of Escher and Heim.Supplementary material: The electronic supplementary material contains all the German original quotations which are embedded as English translations in the present chapter. They have been freely translated by the author and are available at https://doi.org/10.6084/m9.figshare.c.3258481.v1