The Appalachian Mountains are older than the Rocky Mountains.

The Appalachians were formed approximately 480 million years ago during a series of geological events, including continental collisions. In contrast, the Rocky Mountains are much younger, having formed around 80 million years ago during the Laramide orogeny. The age difference between these two mountain ranges is significant, as the Appalachians have been eroded over millions of years, resulting in their characteristic rolling hills and rounded peaks. In contrast, the Rockies are characterized by more rugged, jagged peaks due to their relatively recent formation. This age difference contributes to the distinct geological features and ecosystems found in each range.