Mountain phases refer to the distinct stages of mountain formation and evolution. These phases typically include initial uplift, erosion, and eventual stabilization. During the uplift phase, tectonic forces push the Earth's crust upward, creating mountains. As mountains rise, they are subjected to erosion from wind, water, and ice, which gradually shapes their features. Over time, mountains may become less steep and more rounded, entering a stabilization phase where erosion balances with uplift. This cycle can take millions of years and is influenced by factors such as climate and geological activity.