Elevation crater

The elevation crater theory started in the 18th and 19th centuries and was an attempt to explain the origin of mountains and orogens. The theory held that mountains formed by vertical movements associated with volcanism.[1]

The idea held that magma and volcanic activity formed mountains was expressed as early as 1777 by Peter Simon Pallas, who claimed the Urals and Altai Mountains had formed that way. Pallas based his ideas by an granitic central axis that he had observed in those mountains.[2] The theory was revived and elaborated further by Leopold von Buch in the 19th century.[1] Observations supporting this view were also given by Alexander von Humboldt in his book Kosmos.[2]

Humbold and Buch considered basaltic volcanism to be linked to elevation craters and trachyte to be the product of "true volcanoes".[3] Otto Wilhelm Hermann von Abich applied the theory to the Caucasus Mountains and, following the views of Buch and Humboldt, linked mountain building to volcanism, which led him to take interest in the volcanoes of the Caucasus in the area.[3][4]

The geologist Bernhard Studer refined the idea further. Working in the Alps, he considered the mountains to be roughly symmetrical with a Mittelzone containing the igneous rocks that he believed had uplifted the Alps. The rocks were grouped in twelve Centralmassen. To the north and the south of the Mittelzone were two equivalent marginal zones: Nörliche Nebenzone and Südliche Nebenzone.[2] The theory, as posited by Studer, was popular among geologists in Switzerland and nearby areas until the 1870s.[5]