Geosyncline Theory

The dominant explanation for mountain building from the mid-nineteenth century until plate tectonics replaced it: a geosyncline is a long, subsiding trough that fills with sediment eroding off adjacent uplands, and enough lateral crustal compression eventually folds and uplifts that accumulated sediment pile into a mountain range. James Hall outlined the idea for the Appalachians in a presidential address to the American Association for the Advancement of Science, delivered in 1857 but not published until 1883; James Dwight Dana named and generalized Hall's model in 1873, coining geosynclinal, soon shortened to geosyncline. The theory was adapted rather than dropped outright through the early plate-tectonics era, John Dewey and John Bird recast it in plate-tectonic terms as late as 1970, before Celal Sengor's 1982 critique argued the term itself now carried more discredited baggage than explanatory value, after which geosyncline fell out of active use in favor of the passive-margin, foreland-basin and accretionary-wedge concepts plate tectonics supplies directly.