Appalachian Mountains | Georgia's Physical FeaturesHow Long Is The Appalachian Mountain Range? Visiting Rocky Mountains, Mountain Range in North America, United StatesInside The Appalachian Mountain Club's Lake of the Clouds HutWhere Do Mountains Come From? | Geology for KidsThe Appalachian Mountains, often called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They once reached elevations similar to those of the Alps and the Rocky Mountains before experiencing natural erosion. The Appalachian chain is a barrier to east-west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east-west.