geosyncline

thumb|280px|Development of a mountain range by sedimentation of a geosyncline and isostatic uplifting. This is the "collapse" of the geosyncline. A geosyncline (originally called a geosynclinal) is an obsolete geological concept to explain orogens, which was developed in the late 19th and early 20th centuries, before the theory of plate tectonics was envisaged. A geosyncline was described as a giant downward fold in the Earth's crust, with associated upward folds called geanticlines (or geanticlinals), that preceded the climax phase of orogenic deformation.

==History== The geosyncline concept was first conceived by the American geologists James Hall and James Dwight Dana in the mid-19th century, during the classic studies of the Appalachian Mountains. Émile Haug further developed the geosyncline concept, and introduced it to Europe in 1900. Eduard Suess, a leading geologist of his time, disapproved the concept of geosyncline, and in 1909 he argued against its use due to its association with outdated theories. This did not prevent further development of the concept in the first half of the 20th century by Leopold Kober and Hans Stille, both of whom worked on a contracting Earth framework.