Giant's Causeway | National Geographic

Along the coastal cliffs of Northern Ireland's coast is an unusual geological formation: Giant's Causeway.

About National Geographic:
National Geographic is the world's premium destination for science, exploration, and adventure. Through their world-class scientists, photographers, journalists, and filmmakers, Nat Geo gets you closer to the stories that matter and past the edge of what's possible.

Get More National Geographic:

Giant's Causeway | National Geographic

National Geographic

[MissRoseDarrensAngel]

I've been there with my best friend who lives 2 hours from there, and its an absolutely gorgeous sight to see !

[erikk]

Let’s think about it. We’ll start by simplifying the problem. Imagine you pour hot lava over a completely flat landscape. Something like Bonneville salt flats. Imagine you had so much lava that if filled the landscape to say 100′.

OK. A few things to note.

Lava is very hot and a fluid. Because it’s a fluid the temperature would be very uniform. If there was a really hot area, heat would flow out of that area until the temperature was uniform. So in any direction along the surface the temperature would be the same. There would be no horizontal “thermal gradient”.
Eventually the lava would solidify into basalt stone. It would still be very hot, but it would no longer flow.
Basalt is a good insulator. If you think about the profile of the basalt, the surface would cool quickly, but below the surface it would stay warm because the deeper you go, the more insulation it is. This means there is a vertical thermal gradient.
OK, so now we have a very hot, very flat chunk of rock of that is cooling. As it cools, from the surface down, each “layer” is also shrinking. Since the surface is cooling fastest it is trying to shrink fastest too. When it shrinks it sets up a stress gradient. This gradient will look just like the thermal gradient. It will be uniform horizontally, but vertically it will change with depth.

When the stress gets high enough the rock will eventually crack. Once it does crack, the cracks will propagate. So now we have two questions:

What will the pattern of the cracks be on the surface?
Once there are crack patterns, how will these propagate?
The second question is easier. The cracks will start at the surface. How deep will they be? Well since there is a thermal gradient (and thus a stress gradient) as the cracks propagate down they eventually stop because the rock below is still hot and hasn’t had time to build up stress. Eventually rock at that depth will cool a bit more until the crack opens up a bit more. Keep at it long enough and you’ll see the crack propagate from the surface, vertically down all the way through the layers, until it’s reached then bottom of the basalt layer.

So now the hard part. We know that whatever pattern the cracks start with will propagate down into columns. But why hexagons? Well, starting a brand new crack is hard. The stresses must be VERY high to do it. I don’t mean to anthropomorphize the cracks, but you can think of it this way. Cracks seek to release as much stress as possible for the smallest possible crack.

So what patter breaks up the surface with the least total distance? This is the problem of “tiling a plane” or “tessellation”. There is some rather complex math to prove it, but it turns out that the shape that tiles a plane with the least edge length is a hexagon. If the cracks “choose” hexagons at the surface they will release the greatest horizontal stress for the least amount of cracking.

So there you go. A perfectly uniform lava flow will crack at the surface to relieve stress. Cracking in a hexagon pattern relives the maximum stress per unit crack. Once started the vertical stress gradients in the lava flow will propagate these hexagonal cracks vertically thus forming the familiar columns.

[TubesAXk]

The Giants' Causeway appears on the cover of Led Zeppelin's album Houses of the Holy.

[verily]

In reality this place is unbelievable. No picture can do justice. It is mind blowing .

[RandomnessTube.]

northern ireland's greatest tourist attraction in my eyes from a local.

[kalle]

"he had a problem with.." I expected him to say alcohol.

[marlenagalecka]

Was there last week, found it quite interesting. Also Dunluce Castle and The Dark Hedges not bad :)

[ozzy]

i have been there! Ireland was an amazing experience i suggest you go there no matter what

[machi]

We have in the Philippines too.. waterfall with columns like that..

[yogipl]

I love Ireland!I was living in Tyrone.

[dcagoogle]

I am astonish. Nature creation always beautiful.

[AbhishekChauhan-htvi]

You people should come here, I have found hundreds of ancient giant pillars. Pillars height is around 10 to 20 feet. Comment down for more information.

[DeerFox]

i have been here and i crossed the rope bridge it was so cool

[ariverasan]

wow musta been crazy for such an anomaly to happen with stone, its beautiful

[maryizme]

That was so fun let's do it again!

[fsu-chorgz-]

Reminds me of the DragonMalte Trench or World Scar from ark survival evolved

[Ericanious]

"The Giant built a bridge to Scotland, but scientists ...are about to ruin everything fun about that fucking story!"

[jxgohii]

A video game actually brought me here ...in a meandering way. I began playing Dragon Age Inquisition on Ps4 in 2015 and I remember the hexagonal geological formations looking fascinating. In some areas there were spiders inside the formations - caverns - that led from one area to another, and in other areas of the game were dragons( not inside the caverns, I only found them on the outside Only when watching a t.v show that I stumbled across this. I had no idea this was a place on Earth that inspired the video game.

[jrmhrpr]

Not that I am saying it could not have been done by nature, but why do we not see this in any other part of the world? Only time I have seen shapes like these in nature is crystals. Anyone know what kind of rock that is? Also is there a correlation with crystal formation?

[patefutch]

I wonder how many people seen the door way and didn’t have a camera