Mountains don't actually get *rounder* over time. Instead, they experience a process called erosion, which wears them down, making them shorter and more rounded in appearance.

Here's how it works:

* Weathering: This is the initial breakdown of rock by forces like wind, rain, ice, and temperature changes. It creates smaller pieces of rock, like sand and gravel.

* Erosion: These broken-down pieces are then moved away from the mountain by wind, water, or glaciers. This constant removal of material slowly shapes the mountain.

Here's how erosion makes mountains rounder:

* Sharp peaks and edges: The sharpest points and edges of a mountain are the most exposed to weathering forces. They break down faster, making the mountain less jagged and more rounded.

* Valley formation: As erosion carves valleys, the remaining high points become more prominent, creating a rounded appearance.

* Glacial smoothing: Glaciers are powerful agents of erosion. As they move across mountains, they scrape and polish the rock, creating smooth, rounded features.

It's important to note that:

* Erosion is a slow process: It takes thousands, even millions of years for a mountain to be significantly eroded.

* Other factors: The rate of erosion depends on the type of rock, climate, and other factors.

So, while mountains don't get rounder in a literal sense, the process of erosion makes them appear less sharp and more rounded over vast periods of time.