Here's why:

* Young mountains are formed by recent tectonic activity: This means they are still actively being uplifted and sculpted by forces like erosion.

* Erosion is a powerful force: Weathering (breaking down rocks) and erosion (transporting those broken-down materials) constantly shape mountains. In young mountains, erosion hasn't had enough time to significantly round off the peaks.

* Young mountains have sharp, jagged peaks: These peaks are a result of the intense folding and faulting that occurs during mountain formation. This gives them a characteristically rugged and angular appearance.

Examples of young fold mountains with sharp peaks:

* The Himalayas

* The Alps

* The Andes

Rounded peaks are characteristic of older mountains: Over millions of years, erosion wears down the sharp peaks of mountains, leaving them with rounded summits and gentler slopes.

Here are examples of older mountains with rounded peaks:

* The Appalachian Mountains

* The Ural Mountains

* The Scottish Highlands

Let me know if you have any other questions about mountains!