What controls the height of the world's mountains?

A new study comes to answer an interesting question. What determines the height of the earth's mountains?

Mountains are formed as a result of plate tectonics, the theory that describes the movement of the earth's tectonic plates. There are 3 main mountain formation processes which result in Volcanic, Fold, or Block mountains.

• Volcanic mountains are formed as a result of volcanic activity triggered by the movement of tectonic plates as magma is forced outside of the earth's crust.
• Fold Mountains emerge in the convergence zone between 2 tectonic plates where one is subducting beneath the other. As one plate is on top, material is forced upwards and forms mountains.
• Block Mountains are formed as a result of faults in the earth's crust. In reverse faults, one block is elevated creating mountains while in normal faults, depressed regions known as grabens are created.

Watch, in the Media below, an interesting video that illustrates the mountain formation process.

Scientists from the University of Münster and the GFZ German Research Centre for Geosciences studied the factors that control the height of mountains and made an impressive discovery. They found out that mountain peak heights are mainly correlated with megathrust shear forces in the earth's crust. 

The study was recently published in Nature Communications.

This discovery is in contradiction to a common belief that mountaintop heights are controlled by rock weathering and erosion. In particular, scientists proved that erosion and weathering processes as well as glacier impact had minor effect on the altitude of the studied mountains. 

The research team collected data of mountaintops that emerged on plate boundaries in various regions across the globe (Japan, Andes, Sumatra and Himalayas). For a given case, they calculated the strength and the distributed stresses along the plate boundaries to determine the forces that created the mountaintops. Finally, they implemented a force equilibrium and found out that the forces from the characteristics of a mountain (weight and height) are equal to those forces on the tectonic boundary.

Moreover, this equilibrium was present in all cases studied despite the fact that those mountains are located in different climate environments and are subjected to divergent erosion and weathering processes.

Therefore, the study concludes that height alterations in mountains are a result of alteration in the equilibrium of the forces and are not associated with environmental factors.

These radical findings could provide a whole new perspective on the mechanism of mountains' formation and initiate further future investigation on the earth's crust behavior.