Here's why:

* Mountain Formation: Mountains are formed through tectonic plate collisions, where the Earth's crust is pushed upwards. These collisions can happen over millions of years, resulting in mountains of varying ages.

* Erosion: Once mountains are formed, they are constantly subject to erosion by wind, water, and ice. This erosion wears down mountains over time, making older mountains generally lower than younger ones.

Examples:

* The Appalachian Mountains in North America are some of the oldest mountains on Earth, formed around 480 million years ago. They are significantly lower than the Himalayan Mountains, which are much younger (formed around 50 million years ago) and are the tallest mountain range on Earth.

In conclusion: While age and height are related to mountain formation, there is no direct correlation. Older mountains have had more time to erode, making them generally lower than younger mountains.