What term describes the natural process of mountain building?

The term that describes the natural process of mountain building is orogeny. Orogeny refers specifically to the geological processes that lead to the lifting of the Earth's crust, resulting in the formation of mountain ranges. This process often involves a combination of tectonic forces, including the collision and convergence of tectonic plates, which can lead to the folding, faulting, and uplift of rock masses.

Orogeny is significant because it not only shapes the physical landscape but also influences various ecological and climatic conditions in the regions where mountains are formed. Understanding orogeny is key to studying the Earth's geological history and the dynamics of plate tectonics.