Fancy walking all the way from Springer Mountain in Georgia in the United States to Slieve League and onto BenNevis in Scotland? All this is possible on the International Appalachian Trail which stretches not only across an ocean, many countries, and also aeons of time.
Geological evidence shows that the Appalachian Mountains, some mountains of Western Europe, and the Anti-Atlas range in North Africa are parts of the ancient Central Pangean Mountains and sections later drifted to their present locations. This inspired the International Appalachian Trail people to extend its trails into Western Europe and North Africa.
This is a map of what we normally consider to be the Appalachian mountains in the US. The original Appalachian Trail was a 2,175-mile (3,500 km) hiking trail that ran all the way from Mount Katahdin in Maine to Springer Mountain in Georgia, passing over or past a large part of the Appalachian system. The Adirondack Mountains in New York are sometimes considered part of the Appalachian chain but, geologically speaking, are a southern extension of the Laurentian Mountains of Canada. The Ouachita Mountains in Arkansas and Oklahoma were originally part of the Appalachians as well but became disconnected through geologic history.
The wonderful WalkNI website has lots of useful information about the section of the IAT located in Ireland. Also it seems there are posts for walkers – discovered this on Hike Cycle Ireland – a website I must explore. The writer explains that SIA is the French for International Appalachian Trail (Sentier international des Appalaches in French)