This is the first in a series titled “Ancient Alabama,” examining the natural forces that have made Alabama what it is for the past 500 million years, and how these forces still shape it. State today.
Each year, thousands of people visit Alabama’s Cheaha State Park to see the state’s tallest peak, climb the steps of the observation tower built at the top, and take in the view that stretches for Kilometers and kilometers in each direction.
It’s easy to see why Cheaha was Alabama’s first state park, why the Civilian Conservation Corps built this lookout tower in 1933, and why so many people make the roughly 30-minute trip today. south of Anniston to see the summit and climb the tower.
But I prefer the second highest point in the state. It is a perch on a giant boulder about 100 meters from the current summit of Cheaha. To my untrained eye, it appears to be almost as high as the true summit, which sits at 2,407 feet above sea level, but it is more secluded. You don’t have to stand in line to go up the tower steps or wait for the woman at the top to ask someone on the ground to take a picture of her.
You won’t get the panoramic view of eastern Alabama that you would get from the tower or from the park’s Pulpit Rock or Bald Rock, but if you face the tower and the road to it, you can almost forgetting that you are in a state park with paved roads and some sort of decent cell phone service.
You can just sit on the cool, hard sandstone that has been around for millions of years, watch the trees growing around the rocks, and the birds and butterflies coming in and out of them. It’s quiet enough to hear the fall leaves falling from the trees and rustling to the ground below.
The birds, squirrels, and insects that scattered upon your arrival begin to reappear and show the depth of the forest wildlife tapestry. You can begin to imagine what it might have been like before there was a tower or a state park or asphalt or cell phones.
Many people don’t think of Alabama as a mountainous state. Maybe it’s because they’ve never been to Cheaha or Lookout Mountain. It may also be because they are too focused on the present.
Look back a few hundred million years ago, and Alabama had some of the tallest mountains in the world, possibly taller than any on Earth today.
Solve an ancient mystery
Understanding what high mountains looked like hundreds of millions of years ago is a bit like piecing together a crime scene long before humans roamed the Earth. All of the mountains on Earth will eventually erode if given enough time, leaving little indication that they have ever been there.
A sign at Cheaha State Park boasts that the mountain range that included Cheaha was once twice as high as Mount Everest is now. This is higher than most estimates of the height of these mountains, but there is a lot of uncertainty.
Jim Lacefield, a retired professor and author of the book “Lost Worlds in Alabama Rocks”, said that it was impossible to estimate the height of the Alabama mountains with a high degree of accuracy, so he stayed at the deviation from comparisons with specific peaks like Everest.
He does, however, refer to these mountains as “Alabama’s lost Himalayas,” claiming that the mountains could at least have rivaled today’s tallest peaks.
When trying to learn more about mountains that are long gone or have already eroded significantly, geologists look for clues as to how rock layers tilt in the earth and what types of rock metamorphic that are found at the base.
The inclination of the rock layers can provide clues about the force generated when the continents collided and the location of the highest peaks.
The mountains that remain today are hardly a shadow of what existed before. There’s a prime example of this in DeKalb County, according to Lacefield, where Lookout and Sand Mountain face each other in a lush valley.
If you drive on Alabama Highway 35 from Rainsville to Fort Payne, you can see layers of rock where construction crews cut Sand Mountain to build the road. These layers show the ancient sedimentary rock that accumulated in flat layers over millions of years before being pushed into the mountains.
If you continue a few miles southeast into Will’s Valley and through Big Wills Creek, you will see the same type of rock layers where the roads go up Lookout Mountain.
What you probably won’t notice, but geologists like Lacefield have, is that these rock layers are almost perfect mirror images of each other. So perfect, in fact, that they show that once upon a time, Lookout Mountain and Sand Mountain weren’t two separate peaks at all, but two sides of the same mountain, which the wind and water wore away. for millions of years.
“These opposing rock layers exposed on either side show that this valley was not formed by simple erosion carving out a flat plain, but rather by a wide arching fold in the earth’s crust,” Lacefield writes. “What was once to be a huge folded mountain has been transformed by erosion over time into the picturesque valley that exists today.”
The African collision
What forces could create such massive peaks? Just the African continent, moving rapidly to crash into the rest of Earth’s landmasses to create Pangea, the supercontinent.
Lacefield says you can imagine mountains forming the same way dirt is accumulated by the blade of a bulldozer.
Dating back 500 million years, Alabama was primarily underwater and well south of the equator, slowly drifting north into the tropics. It lasted around 200 million years when these drifting continents began to collide.
The different land masses had essentially consolidated into two large continents: one called Laurasia, containing what is now Europe, North America and part of Asia, and the other, Gondwana with Africa, South America. Then, about 323 million years ago, Gondwana swooped down on Laurasia, pushing all those mountains up and creating the Pangea supercontinent.
The continent didn’t stop on a dime, but continued to grow and grind northward for millions of years, piling mountains up as it went. In Alabama, Lacefield said the mountain-building event likely peaked around 299 million years ago, pushing mountains to their highest points, whatever they may have been.
Alabama’s “Lost” Desert Years
After the collision, the Alabama went from being almost completely underwater to being pushed over the sea and surrounded by land on all sides. Now landlocked and dry, Alabama was essentially a desert. And we don’t know much else about it.
Lacefield says there is a gap of over 200 million years in the state’s geological records from this time, and no rocks found here have formed during that time. Most of the rocks we have in Alabama were formed from marine sediment, which means they were created when runoff flowed into the ocean and hardened into rock.
With Alabama now far from the nearest ocean, this sediment has been transported elsewhere and left no trace here. This would continue until Pangea parted ways and Alabama regained a shoreline, during the time of the dinosaurs.
This is a story that we will pick up in the next episode of Ancient Alabama, when we meet the Appalachiosaurus, an evolutionary cousin of the famous Tyrannosaurus Rex and the supreme predator of the tropical jungles of Alabama around 80 million years ago. years.