Major North American mountain range stretching from
Quebec to
Alabama. They posed a major barrier to
westward
expansion in the early years of
white settlement.
Like the Rocky Mountains, the Appalachians were created by the collision of large tectonic plates in a series of orogenies or mountain building episodes. Unlike the Rockies, the Appalachians are old and eroded. The east coast of the United States and Canada has been a passive margin for the last 200 million years.
During this time no tectonic activity has been taking place on the margin of the Appalachians and the only geologic events to occur were erosion and sedimentation as rivers carried sediment to be deposited on the continental
margin.