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Geology of Appalachia: What makes our home unique

Updated: Apr 25, 2023




The Appalachian Mountains hold a place in many hearts and lives. Appalachia is a place as well as a sense of feeling. However, the physical appearance of the mountains is not only beautiful but also fascinating geologically.


There are interesting events that happened long ago to make Appalachia what it is known as today. Although current society has not lived to see the significant changes that have formed Appalachia, people can learn through science how our home came to be.


The Appalachian Mountains formed 480 million years ago in the Ordovician Period. The Ordovician Period was the second of six periods of the Paleozoic era. According to the United States Geological Survey, the Paleozoic era means, in simple terms, ancient. Most plants and animals that existed in the Paleozoic era do not still exist today.


Stretching 2,000 miles and through seven states from Newfoundland and Labrador to Alabama, the Appalachian Mountains are vast. There is a climate difference as well in these mountain ranges.


Canada has a much colder climate than the farthest point of the mountains in Alabama. Therefore, the Appalachian Mountains are more diverse than most people assume. They are known for mixed forests and notable parks. Every region is different in its own way; however, it is still one mountain range.


Michael Whitelaw, professor of geosciences at East Tennessee State University, shared his thoughts on how Appalachia compares to other mountain ranges.


“There’s one thing we have to be careful with when talking about the Appalachians, that’s the mountain range that we have here today,” said Whitelaw. “It is a result of modern erosion.”


Whitelaw explained that the Appalachian Mountains formed due to a series of tectonic events.


“These tectonic events started when Europe formed what was called Baltica collided with Laurentia, which is what we call North America, and that happened mostly in the northern part of the Appalachians,” said Whitelaw. “Then we have a second event called the Tectonic Orogeny; after that was the Acadian Orogeny, and finally we have the Hellenic Orogeny—that orogeny mostly impacts us.”


The Hellenic Orogeny led to multiple mountains being formed all over the world.


“Africa collided with the southeastern part of the United States, so most of the faults around the area of Appalachia are related to that orogeny,” said Whitelaw. “That happened around 300 million years ago, so the mountains were formed and then have been eroded pretty much flat, and then recently they have uplifted just a little bit, with what is called rejuvenation to make what we have today.”


A comparable mountain range in the United States is the Rocky Mountains. Although the Rockies differ from the Appalachian Mountains, they have some commonalities.


“The Rockies were formed maybe 100 million years ago and are still being formed today in some parts, especially if you look at the Cascades and those areas as well,” said Whitelaw. “It’s like comparing apples and oranges.”


Time has changed mountain ranges all over the world in many ways. Erosion and rejuvenation are examples of how mountain ranges change over time, but many do not know what was before the Appalachian Mountains.


“If you really want to go all the way back in time, there was a mountain range before the Appalachian Mountains in the same area, we still see those rocks in the Smoky Mountains and in a few places along Interstate 26,” said Whitelaw.


A mountain range that formed from Pangea travels farther than anyone could imagine any mountain range to this day.


“The mountain range that formed from the Pangea collision can be traced through where the Appalachians are today, across to Texas, and then across to Antarctica, then into Australia,” said Whitelaw. “It was an enormous mountain range, far bigger than what the Rockies are today.”


The mountain range from Pangea eventually eroded down and broke apart. The ocean then formed and the continents re-collided. The rocks that are here present day are from that collision.


The Appalachian Mountains have been around for a long time, but people must be reminded of the geological advances that made the mountains in the first place. Although no one can fathom how long ago 480 million years is, they can understand the history of where they live today.


Photo 1 provided by Blue Ridge Mountains Travel Guide. Photo 2 provided by National Park Service.

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