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Are the Smoky Mountains Older Than the Rocky Mountains?

Have you ever wondered about the age of the mountains in the United States? While the U.S. is relatively new as a country, the mountain ranges that stretch across the land are far from recent. One of the three major mountain ranges in the U.S. is hundreds of millions of years old.

Compare it to the newest mountain range in the Sierra Nevada, which is only around 40 million years old. Keep reading to learn more about the two oldest mountain ranges in the U.S.; the Smoky Mountains and the Rocky Mountains. 

Let’s get started!

About the Smoky Mountains

The Smoky Mountains are a subrange of the Appalachian Mountains. The Appalachian Mountains are the oldest in the U.S. This mountain range also claims to be the most visited U.S. National Park, the Great Smoky Mountains National Park.


The Appalachians span 13 states, including Kentucky, Tennessee, Virginia, Maryland, West Virginia, North Carolina, Alabama, Georgia, South Carolina, Pennsylvania, Ohio, New York, and Mississippi. They also extend slightly into Southeastern Canada. A couple of the subsets of the Appalachians include the Smokies and the Blue Ridge Mountains.


Spanning 13 states and into Canada, this mountain range is by no means small. Around 200 miles wide and approximately 2,000 miles long, the Appalachian Mountain Range creates a natural barrier between the eastern coast and interior lowlands of the U.S. It takes up an impressive 471 million acres, with the Smoky Mountains being only 522,000 acres.

When Were the Smoky Mountains Formed? 

The Smoky Mountains, as a part of the Appalachian Mountain Range, are the oldest in the U.S. Their formation began around 480 million years ago around the time of the construction of the supercontinent, Pangaea. At that time, Africa and North America were one, so Little Atlas, a mountain chain in Morocco, was also part of the formation of the Appalachians. 

Around 40 million years later, the quiet of the now Appalachian chain was drastically changed when tectonic plates collided and created a subduction zone when one plate goes below another. As an active plate boundary, the Appalachians rose, but over time erosion began to break them down. Fast forward 250 million years, and these mountains have eroded to an almost flat plain.

It wasn’t until another 50 to 100 million years after that that the Appalachians (including the Smoky Mountains) took on the shape they are today. Instead of high elevation and jagged peaks, the Appalachian Mountain chain has majesty with its broad ridges, deep canyons, and wide valleys covered in a thick canopy of evergreens.

Pro Tip: Spend the night at one of these Best Free Camping Spots Near the Smoky Mountains.

Man hiking in the Rocky Mountains
The Smoky Mountains and the Rocky Mountains are steeped with years of history.

About the Rocky Mountains

While portions feature evergreens, the Rocky Mountains drastically differ from the Appalachians’ topography. They are more prominent in structure and familiarity, but this mountain chain is one of the youngest in the world.


The Rocky Mountains are an anomaly for major mountain chains as they are not near a coastal region. Some portions of this mountain chain are around 1,000 miles from the nearest coast. Part of the Great Divide, it separates the flow of the rivers draining into the Pacific or the Atlantic and spans two Canadian provinces and seven states. Those provinces are British Columbia and Alberta. The seven states include Washington, Idaho, Montana, Wyoming, Utah, Colorado, and New Mexico.


The Rocky Mountains may be younger than the Smoky Mountains and the Appalachians, but they are similar in size. While the Appalachians claim more acreage, the Rockies are the most extended mountain range in North America at around 3,000 miles. Like the Appalachians, they are approximately 300 miles wide but only encompass 245 million acres compared to the 471 million acres that comprise the Appalachian Mountain chain.

When Were the Rocky Mountains Formed? 

While they are young, the interior of the Rocky Mountains contains pieces of the Earth’s crust that scientists have dated to over one billion years old. The Uncompahgre Range, along with the Ancestral Rockies, was also once a part of these pieces. However, erosion and weathering have long since leveled the peaks.

Their ancestors, the Rocky Mountains, came into existence hundreds of millions of years later, about 70 million years ago. They emerged through flat-slab subduction, where one plate goes under another plate at a shallow angle.  The substantial friction from the plate activity combined with glacial erosion helped shape the jagged peaks of the Rocky Mountains.

Only coming into existence less than 100 million years ago, the Rocky Mountains are one of the youngest mountain chains on the planet.

Scenic view of the Rocky Mountains
Connect with nature while hiking through the Rocky Mountains.

Are the Rocky Mountains Still Growing Today? 

Because they are so young, the Rockies’ growth is far from over. However, their growth will not be something we see in our lifetimes. Mountains take hundreds of millions of years to form and grow, and within that time, they peak and erode. That’s why the older mountain ranges of the world generally lack high elevations and jagged peaks.

Since the Rocky Mountains have only just begun growing, they have much growing up to do. Volcanoes and tectonic movement will continue to shape the Rockies. They are still rising, so they will eventually erode, with the remnants depositing on the high plains. However, this won’t happen in our lifetime.

Pro Tip: Beware of these Most Dangerous Creatures in the Rocky Mountains on your adventure.

Are the Smoky Mountains the Oldest Mountain Range in the World? 

While the Appalachian Mountains, including the Smoky Mountains, are the oldest mountain range in the U.S., it is not the oldest mountain range in the world.

That title belongs to the Barberton Greenstone Belt, the Makhonjwa Mountains in the Mpumalanga province of South Africa, and the border of Swaziland. At around 3.6 billion years old, this area has some of the most ancient exposed rocks on Earth. Not only that, but due to extraordinary preservation throughout the chain, scientists gained an understanding of life on earth when it was all evolving. Because of this, people have often called the Makhonjwa Mountains the Genesis of Life.

The Appalachians are still in the top ten oldest mountain chains, giving insight into the North American continent and the world.

Three friends hiking in The Rockies
Hikers will love trekking through the Rockies and the Smokies.

Why Are the Smoky Mountains No Longer Growing? 

A mountain range as old as the Smokies and the Appalachians have been growing for hundreds of millions of years, even into the billions. When a mountain chain starts, generally, tectonic plates come together to create friction that causes the land to buckle. When mountain chains are young, they are at their peak. 

As they age a few hundred more million years, erosion begins, eventually flattening most peaks. It is because of their age that the Appalachian Mountains are no longer growing. Instead, they have been eroding for millions of years. The erosion rate is about six meters per million years. 

Just as you will never notice the growth of the young Rocky Mountains, you will never see the decline of the ancient Appalachian Mountains.

Which Mountain Range Has the Highest Peak: Smokies or Rockies? 

The Smoky Mountains, as a subrange of the Appalachians, can lay claim to some high peaks, but none of them, including the Appalachians, come close to the peaks in the Rocky Mountains.

Over 100 major peaks in the Rockies, and 78 are in Colorado. Thirty are the highest of all Rocky Mountain peaks. Mount Elbert in central Colorado near the mountain town of Leadville is the highest peak in the Rockies at 14,440. It’s also the highest peak in Colorado and the second highest in the contiguous United States. It is second only to Mount Whitney in the Sierra Nevada in California.

By comparison, the Smokies’ highest peak is Clingmans Dome at 6,643 feet, the Appalachian Mountain Chain’s second-highest peak. The first is Mount Mitchell, at 6,684 feet, in the Blue Ridge Mountain subrange of the Appalachians. 

Are the Smoky Mountains and Rocky Mountains Worth Visiting?

Six thousand or 14,000 feet, the peaks of the Smokies in the Appalachians and the Rocky Mountains are worth visiting. From the mist-shrouded, tree-covered canopies of the age-old Appalachians to the rugged snow-capped peaks of the young Rockies, there are stunning vistas, deep canyons, and flora and fauna that call both places home. Young or old, these mountain chains are full of wisdom beyond any we could ever dream of having, no matter how old we get.

Have you visited any of the Smoky or Rocky Mountains? 

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