What Is the Difference Between a Young and an Old Mountain?

Buena Vista Images/Photodisc/Getty Images

The major difference between young and old mountains is the level of erosion within an entire mountain range. For example, the Rocky Mountains and Himalayan Mountains are young because they are still rugged, with very few signs of erosion. These mountains are still uplifted due to tectonic forces. The Appalachian Mountains and Ozark Mountains have flatter tops and have been eroded longer, so they are older.