<P> The Appalachian Mountains ( French : les Appalaches ) , 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 . </P>
<P> The Appalachian Mountains ( French : les Appalaches ) , 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 . </P>
which mountains are higher the rockies or the appalachians
which mountains are higher the rockies or the appalachians
Rocky Mountains
Rocky Mountains