The theory of undercurrent from the Austrian alpine geologist Otto Ampferer (1875–1947): first conceptual ideas on the way to plate tectonics1

In his paper “Über das Bewegungsbild von Faltengebirgen” [On the movement pattern of folded mountains], published in the almanac of the Austrian Geological Survey in Vienna, Otto Ampferer from Innsbruck (Austria) presented a series of geotectonic considerations and interpretations, which today are summarized under the term “theory of undercurrent”. The interpretation of these processes occurring in the deep crust of the Earth and in the upper mantle was mainly kinematic. For a long time, the tectonic passivity of the magma being anorogenic was dogma until Ampferer’s undercurrent theory changed this in 1906, according to which folds and thrusts on the Earth’s surface portray motions of the deeper magmatic substratum. In these undercurrents, Ampferer recognized the crucial forces that lead to the formation of ocean basins and high mountains on the edges of the drifting continents. In his paper on the history of the formation of the Atlantic region, he presented already, in 1941, a process anticipating what is now known as seafloor spreading.