Building a highway thru rough ground…

[billanole]

The inside story of why rockslides on Interstate 40 will never stop

More than 50 years ago, it wan't common to include geologists into conversations about highway design. And we're living with the headaches today.

www.citizen-times.com

There's an infamous stretch of highway that twists and turns through the rugged border mountains that separate Tennessee and North Carolina.

Interstate 40 is known for its stunning views of the Pigeon River, its steep grades and its steady stream of long-haul semis. But it's also notorious for frequent and crippling rockslides that shut down the highway for days.

Why do slides happen so often?


We may get a lane open in each direction by the end of year.

 

[tarheelbybirth]

We may get a lane open in each direction by the end of year.

Probably still be faster to go through VA.

 

[billanole]

Probably still be faster to go through VA.

Or Tennessee via I26.

 

[dekhawk]

It is a beautiful drive.

 

[The Tradition]

Why do slides happen so often?

The Great Smoky Mountains were formed between 200 and 300 million years ago, during a period of intense mountain building known as the Appalachian revolution. The mountains are one of the oldest in the world and are made up of a variety of rock types that span a wide range of geologic time.
The formation of the Great Smoky Mountains was a result of several geologic events, including:

Continental collision
Around 270 million years ago, Africa collided with the eastern edge of North America, creating the supercontinent Pangea.

Tectonic plate shifting
The shifting of tectonic plates caused the underlying metamorphic rock to tilt and slide over the younger limestone rock.

Volcanic eruptions
Around 450 million years ago, the northernmost ranges of the Appalachians experienced massive volcanic eruptions.

Ice ages
The constant freezing and thawing of rock during the ice ages created massive boulders.

Ever since the Earth forced those mountains into the sky, they've been slowly eroding.

 

[billanole]

The Great Smoky Mountains were formed between 200 and 300 million years ago, during a period of intense mountain building known as the Appalachian revolution. The mountains are one of the oldest in the world and are made up of a variety of rock types that span a wide range of geologic time.
The formation of the Great Smoky Mountains was a result of several geologic events, including:

Continental collision
Around 270 million years ago, Africa collided with the eastern edge of North America, creating the supercontinent Pangea.

Tectonic plate shifting
The shifting of tectonic plates caused the underlying metamorphic rock to tilt and slide over the younger limestone rock.

Volcanic eruptions
Around 450 million years ago, the northernmost ranges of the Appalachians experienced massive volcanic eruptions.

Ice ages
The constant freezing and thawing of rock during the ice ages created massive boulders.

Ever since the Earth forced those mountains into the sky, they've been slowly eroding.

The Pigeon River Gorge is made up of low to medium grade metamorphic rock and the seams are vertical mostly. This allows the freeze thaw effect to constantly break off sections of rock, some large, some small. Keeping this route open is a constant challenge.

 

[The Tradition]

The Pigeon River Gorge is made up of low to medium grade metamorphic rock and the seams are vertical mostly. This allows the freeze thaw effect to constantly break off sections of rock, some large, some small. Keeping this route open is a constant challenge.

If you knew the answer, then why did you ask?

 

[billanole]

If you knew the answer, then why did you ask?

I figured you needed something to get stirred up about. Looks like it worked.

 

[NoWokeBloke]

If you knew the answer, then why did you ask?

He;s an attention whore.