How Did Georgia’s Appalachian Mountains Form?

Georgia sits at the southern tail of the Appalachian Mountains, where people have spent thousands of years living in the folds, hills and valleys of these quiet mountains. 

Though not as tall as the Rockies to the west, the Appalachian Mountains are actually some of the oldest mountains in the world! Georgia residents are, quite literally, living on top of some of the oldest geologic formations still around today. 

Here’s how the ancient Appalachians formed, how they disappeared, how they reappeared and, of course, how they got to be where they are today.

Formation and history of the Appalachians

The world back then

The Appalachian Mountains are some of the oldest in the world — the 9th-oldest, to be exact. And they used to be much, much taller.

In fact, at their peak (hah!) the tallest mountains were believed to have been as tall as the Himalayas, which, despite being the highest range in the world today, only formed a mere 40 million years ago.

But, we’re getting ahead of ourselves here. Let’s start at the beginning, back in the early days of the supercontinent Pangea in the Permian Period, around 300 million years ago.

Pangea

The name Pangea (also called Pangaea) is derived from the Greek word pangaia, which means “all the Earth”. A fitting name, for sure, because by the time this supercontinent had finished forming (about 250 million years ago), nearly all the land on the planet was smushed together in a crescent shape in the center of a massive, near-planet-wide ocean. 

This supercontinent was formed by various other continents slowly colliding with each other and joining together over a period of 200 million years. We wouldn’t be able to recognize our current-day continents in this supercontinent, but they were there as smaller parts of larger continents that would eventually break apart later on. 

The continent Laurentia, of which makes up most of modern-day North America, collided with the continent Baltica that today makes up most of Eastern Europe. These two created a minor supercontinent referred to as Euramerica or Laurasia. There was also the minor supercontinent Gondwana, which contained modern-day South America, India, Africa, Antarctica and Australia.

These two minor supercontinents, plus a few smaller land masses floating around, had been slowly joining each other for millions of years, moving closer and closer together as plate tectonics rearranged the surface of the Earth. Finally, by the beginning of the Permian Period around 298 million years ago, the northern shoreline of Gondwana and the southern shoreline of Laurasia collided, forming the supercontinent Pangea. 

Okay, sure. This is great and all, but how does this apply to the Appalachian mountains?

Well, when two massive pieces of and collide with each other, the land on the surface near that seam wrinkles and crumples as the tectonic plates below move under or grind against each other. These kinds of collisions form mountains, and when Laurasia and Gondwana collided to form one super continent, a whole lot of mountains formed along the seam. 

These Central Pangea Mountains, as they are known, were the birthplace of the Appalachian mountains. In fact, there are a few different mountain ranges still in existence today that were in that range along with our very own Appalachians! The Little Atlas Mountains in Morocco, for example, were on the Gondwana side of that seam directly across from the Appalachians. The Scottish Highlands were part of that range, too, including the famous peak Ben Nevis — the highest peak in the United Kingdom and the British Isles. 

These continent-spanning mountains were as high as the modern-day Rockies, Alps and perhaps even the Himalayas — but, they didn’t last very long. Because of their location along such a tumultuous seam and due to an intense amount of weathering, the grand mountain peaks were reduced to half their size by the end of the Permian period 252 million years ago. 

No one likes a long, drawn-out breakup, but at least no one had a break up that lasted 30 million years. Tectonic activity caused the seam between Gondwana and Laurasia to eventually separate, with the newly-created Atlantic Ocean dividing the two continents once more. This separation nearly flattened the once-towering Central Pangea Mountains, and by the early Triassic period 200 million years ago, all that were left were upland areas, hills and flat plains. 

Creating the modern Appalachians

Millions of years passed, during which the world assembled itself into a more recognizable arrangement and creatures like the dinosaurs had come and gone. The world had entered into its most recent geological era — the Cenozoic Era — which encompasses the past 66 million years up to the present day. 

For reasons still unknown to geologists, the flattened and buried mountains on North America’s east coast began to uplift sometime at the beginning of this new era. It may have been a result of the tectonic activity that raised the Rockies in the West, it may have been stress from tectonic plate movement in the Atlantic — no one knows yet. But, nonetheless, the mountains were thrust upward once again, creating the Appalachian mountains. 

The rivers and streams that criss-crossed the landscape prior to the uplift were violently redirected and, as with the New River in North Carolina and Virginia, they cut down through the ancient rocks to form deep canyons and crevasses. The continued erosion washed away the newer sediments on the fledgling mountains, exposing much older rock and rounding out the mountains once again. 

Some of the rocks exposed date back to the Proterozoic age around 1-1.3 billion years ago! This old rock, called gneiss, can be found in the Blue Ridge and Piedmont regions of Georgia! Red Top Mountain in northern Georgia is a great place to see some of this ultra-ancient rock that was made long before the mountains even formed. 

So, if you live in or near our luxury Atlanta apartments, make some time to visit the Appalachian Mountains and see the ancient hills through new eyes. You can also make a trip to the Weinman Mineral Gallery at the Tellus Science Museum, where vast collections of minerals and exhibits on geology can tell you much more about Georgia's ancient history than we can!

Rock on! (Get it? Because rocks.)

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Featured photo courtesy Pixabay/paulbr75