Since long the reason behind the growth of the mountains is sought out by the scientists. But now it seems possible to reason why they grow and how they grow?
According to a new study, rather than erosion at the top or weather conditions, underneath tectonic forces control the growth of a mountain. The mountains located on the tectonic plate collision zones, maximum height can be achieved by an equilibrium of forces deep in the earth’s crust.
Tectonic plates move towards each other and sometimes one plate is forced into earth’s mantle as it buckles and folds. This leads to the rise of mountain ranges. Apart from tectonic movement, there is another factor that causes such movement of the plate. It is called isostasy, which is a process where mountains float on the top of the hot and soft mantle. However, it is considered less significant.
The scientists modeled the different forces that could act on the tectonic plate, in part using heat flow measurements near the surface as a proxy for the underlying frictional energy at play. On comparing these models with real mountain range heights in the Himalayas, Sumatra, the Andes, and Japan, it was concluded that mountains that are still growing, the height and weight stays in balance with the large underground forces. If the friction and stress underneath shifts, so does the mountain height.
“Erosional processes can modulate mountain topography and trigger active faulting as suggested by conceptual and numerical models for climate-tectonic interactions,” write the researchers in their newly published paper.
“However, our findings suggest that erosion is not capable of outpacing the tectonic and isostatic processes that keep convergent margins close to force equilibrium, because the upper plate is effectively weak.”
The researchers liken it to putting your hands under a tablecloth, and then moving them together – the folds of cloth that rise in the middle are the mountains, and the friction of the cloth slowly moving back across your hands is the tectonic activity.
It remains to be seen whether the same is true of mountains that aren’t close to subduction zones, where one tectonic plate is sliding under another – in those cases, it’s still possible that mountain height is limited by climatic conditions, such as the position of the snow line.