Fixism

The Fixismus was up to the paradigm shift of geology relevant in the 1960s geotectonic hypothesis , which today is considered obsolete. It was assumed that the earth's crust is firmly connected to the subsurface, so that large-tectonic processes are local. From this it followed that the development of the earth was mainly shaped by vertical and very little by horizontal tectonic movements of the earth's crust . Most theories of classical geology (for example, the theory of contraction ) were based on the idea of ​​fixism before the theory of plate tectonics was introduced .

The theory of permanence is based on fixism , which teaches that all continents have remained in one and the same place since the formation of the earth's crust. The geosyncline theory as a classical (i.e. pre-plate tectonic) ore formation theory is based on this.

The paleobiogeographical distribution areas of Cynognathus , Mesosaurus , Glossopteris and Lystrosaurus shown here in color are today considered evidence of plate tectonics. Fixism tried to explain the fossil finds on different continents with the land bridge theory.

At the beginning of the twentieth century, fossils of the same animal species were found in South America and Africa. Under the assumption of fixism, the land bridge hypothesis was put forward, according to which there were once land bridges connecting Africa with South America, so that it was possible for the animals to migrate to the other continent. These land bridges are said to have sunk in the course of earth's history . This hypothesis was incompatible with the theory of permanence. Through the echo sounder measurements of the research vessel Meteor in the years 1924 to 1927, during which the mid-Atlantic ridge - an undersea mountain range that runs from north to south - was discovered and not, as expected, residues of a land bridge, which should have run from east to west , the Landbrücken hypothesis faltered, but was not completely abandoned until the 1960s.

The opposite of fixism is mobilism , which regards horizontal movements of the earth's crust as having a decisive influence. The theory of mobilism developed from Alfred Wegener's discovery of continental drift and has been supported by studies of plate tectonics since around 1960 .

See also : history of geology

literature

• Rudolf Hohl (ed.): The history of the development of the earth . 6th edition. Werner Dausien Verlag, Hanau 1985, ISBN 3-7684-6526-8 , p. 235 f .