The Geology of the Oldest Mountains in the World: Vol. 1 - Appalachian Mountains

Generally speaking, when people think of the mountains, they envision colossal snow capped titans that stand miles above the ocean. While those sort of mountains are very impressive, it’s the more modest mountains that are typically overlooked. In this post I’ll be discussing one of the worlds oldest mountain chains, that predates the dinosaurs and are a product of the supercontinent Pangaea itself. Today, we’ll be talking about the unpretentious, yet very dynamic Appalachian Mountains of eastern America.

Photo of the Great Smoky Mountains during the spring time. Image Source: Shot by author of this article.

Stretching from Alabama to the Canadian Island of Newfoundland (1500 mi or 2400 km), the Appalachian Mountains make up the Eastern Continental Divide of America, separating the eastern seaboard from the Midwest. Unlike it’s big brother to the west (the Rocky Mountains), the mountain peaks of the Appalachians are much rounder, its valleys much broader and its lush green forests teem with life. Furthermore, the average altitude throughout the Appalachian belt is much lower than its American counterparts, with the highest peak being Mt. Mitchell in North Carolina, standing at 6,683’.

Topographic map of the Appalachian Mountains. [Image Source]

Overall, the United States Geological Survey (USGS) defines the Appalachian Highlands physiographic division as consisting of twelve provinces:

• Atlantic Coast Uplands
• Eastern Newfoundland Atlantic
• Maritime Acadian Highlands
• Maritime Plain
• Notre Dame and Megantic Mountains
• Western Newfoundland Mountains
• Piedmont
• Blue Ridge
• Ridge-and-Valley
• Saint Lawrence Valley
• Appalachian Plateaus
• New England province

While they may not stand as high as the Rockies, they are much older. Dating back to roughly 480 Ma, the Appalachians distinct look can be attributed to several continental collisions and eons of weathering. Many scientists believe these mountains are in fact the oldest mountains in the world, though this is contested. However, what goes uncontested is that they are home to the second oldest river in the world and it’s ironically named, the New River, which is located in West Virginia. This rivers distorted path along the Appalachians, expose rocks that are well over 1 billion years old. To give you an idea of how geologically old these mountains are, the Himalayan Mountains (home to Mt. Everest), have been dated to be roughly 40 Ma. To say the least, the Appalachian Mountains have truly stood the test of time.

Image of the New River Gorge in West Virginia, which is the second oldest river in the world. [Image Source]

What caused the Appalachian Mountains to form?

When taking a look at the exposed rocks in these mountains, there are elongated belts of folded and thrust faulted marine sedimentary rocks, volcanic rocks and slivers of ancient sea floor. These deformed rocks are evidence that plat collision did in fact occur. As of right now, geologist’s believe the first of several mountain-building plate collisions occurred 480 Ma (Paleozoic Era), during the construction of the supercontinent Pangaea. At one point, North America and Africa collided (known as the Alleghanian orogeny), which makes the Anti-Atlas Mountains of Morocco their long lost separated appendage. These mountains made up a greater group of mountains known as the Central Pangean Mountains, which extended into Scotland and were a product of the North America/Europe collision.

Over the course of 200 million years (Mesozoic Era), these mountains would be practically reduced to a flat plain by erosion and weathering. Then, roughly 66 million years ago (the current geological Cenozoic Era) this region was uplifted once again. This uplift caused streams to rapidly move downward cutting in ancient bedrock, some of which followed weak layers defined by ancient folds and faults. Other streams had such a rapid downcut, they would eventually cut across the folded rocks of the mountain core, creating canyons and other geological features. All of these processes are what created the present day topographical landscape.

Image showing how the waters of the New River slowly cut through the bedrock of the Appalachian Mountains. [Image Source]

Today, the Appalachian Mountains are home to some of the most beautiful sceneries this world has to offer. I can attest to this considering I’ve explored much of the mountain chain myself. One of the more intriguing characteristics of these mountains are the diverse landscapes and climates that come along with it. For instance, the Blue Ridge Mountains of western North Carolina are considered to be a temperate rainforest, that rivals the lush green forests of Pacific Northwest. On the flipside, the Shenandoah Valley in Virginia receives significantly less rainfall due to a strong rain shadow, which occurs from a number of ridges to the west collecting most precipitation moving eastward. Heading further north to Mt. Washington in New Hampshire, some of the strongest winds and coldest temperatures in the world are recorded. All being said, the Appalachian belt is indeed a very dynamic region.

Western Brook Pond in the Long Range Mountains of Newfoundland, Canada. [Image Source]

As a child, I honestly didn’t respect these mountains too much. In hindsight, I was just being naive and was one of those people that were under the impression that mountains were supposed to be massive snowcapped boulders that jutted into the sky. However, after visiting these mountains periodically throughout my life, I can say without a doubt they are by far my favorite geological feature to date. While I could talk about these mountains forever (and I most likely will in future posts), I’ll leave you with a cool story that I shared with my family in Appalachia.

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This is Hazel Creek, which resides in the heart of the Smoky Mountains National Park. [Image Source]

In the Smoky Mountains National Park of western North Carolina there was a very isolated area in the forest called Hazel Creek. Words cannot describe how majestic of a place it truly was. It’s technically a huge water shed that acts as a tribute to the Little Tennessee River, whose waters flow all the way to the Ohio River, then to the Mississippi River and finally down into the Gulf of Mexico. One day our family took a family trip to Hazel Creek and as usual my father just sat on a large rock in the middle of the creek and ran his hand through the smooth gravel sized rocks. Out of no where my father seemed excited and called over the family and asked “Does this look like a shark’s tooth?” Seeing how most of us were born and raised on west coast of Florida, we knew immediately that it was in fact a shark’s tooth. The clear giveaway was the noticeable ridge on the tooth that formed where the sharks gum line would have been. Unlike most shark’s teeth, this one was worn down and very old.

Upon further investigation, my father spoke to a few locals and ran into a guy who actually collected shark’s teeth in the area as a hobby! It blew our minds because we were over 500 miles from the coast. To say the least, this was one of the stories that led me down the path of geology and natural sciences in general. With that being said, I hope this post inspires you to look further into the history of the Appalachian Mountains to discover the abundance of knowledge it has to offer.

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Bibliography:

https://en.wikipedia.org/wiki/Appalachian_Mountains

https://en.wikipedia.org/wiki/Alleghanian_orogeny

https://en.wikipedia.org/wiki/Anti-Atlas

https://www.learner.org/series/modules/express/pages/scimod_34.html

https://www.nps.gov/neri/learn/nature/the-new-river-fact-or-fiction.htm

General knowledge gathered while living in the region.