The Appalachian Mountains are often called the "oldest mountains" due to their formation over 480 million years ago.

The Appalachian Mountains are among the oldest mountain ranges in the world, formed during the Paleozoic Era through tectonic activity as ancient continents collided. Over millions of years, erosion has significantly worn down the once-towering peaks, leaving behind the rounded ridges and valleys seen today. This ancient origin gives the Appalachians their distinctive weathered appearance and has shaped the geology of the surrounding region. Their longevity has also allowed ecosystems to develop, leading to high biodiversity. The title "oldest mountains" underscores their historical and geological significance, standing as a testament to Earth's dynamic processes.