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Author Topic: The Giant's Causeway!! How was this formed?  (Read 10298 times)

Offline Seany

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The Giant's Causeway!! How was this formed?
« on: 26/03/2008 23:04:19 »
How was the Giant's Causeway formed?
For people who don't know what it is.. I recently read about it in a Geographic magazine!



It's all hexagonal! :o


 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #1 on: 26/03/2008 23:04:38 »
My bad.. I think it's more pentagonal ;)
 

Offline Karen W.

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The Giant's Causeway!! How was this formed?
« Reply #2 on: 26/03/2008 23:08:50 »
Its beautiful...It looks man made as far as the hexigonal shapes of those rocks.. but somewhere there was some rocks formed naturally that I would have sworn were formed by man but was natural... maybe heat and water and extreme temperatures or even Volcanic movement or activity..???
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #3 on: 26/03/2008 23:10:01 »
I don't believe it's man-made.... But it looks really cool!
 

Offline Karen W.

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The Giant's Causeway!! How was this formed?
« Reply #4 on: 26/03/2008 23:11:05 »
Yes it does.. quite a eye full! really nice!
 

Offline Karen W.

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The Giant's Causeway!! How was this formed?
« Reply #5 on: 26/03/2008 23:12:07 »
Liked there being pushed up through the earth.. perhapes quakes add to their formations???
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #6 on: 26/03/2008 23:12:57 »
Maybe.. It's fascinating!
 

Offline Karen W.

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The Giant's Causeway!! How was this formed?
« Reply #7 on: 26/03/2008 23:25:11 »
Yes it is.. I hope you find out how it was formed!
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #8 on: 26/03/2008 23:28:19 »
Yes.. Neil will tell me ;D
Or Beaver.. Err.. DoctorBeaver, that was it lol ;D
 

Offline Karen W.

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The Giant's Causeway!! How was this formed?
« Reply #9 on: 26/03/2008 23:31:19 »
Yepperoo.. You have it....
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #10 on: 26/03/2008 23:34:02 »
Yayyyyyyyyyy.. Hope someone has the answers!
 

Offline Karen W.

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The Giant's Causeway!! How was this formed?
« Reply #11 on: 26/03/2008 23:38:36 »
They will..
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #12 on: 26/03/2008 23:40:51 »
YAYYYYYYYYYYY!
 

Offline Bass

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The Giant's Causeway!! How was this formed?
« Reply #13 on: 27/03/2008 00:00:01 »
The Giant's Causeway is basalt, or mafic lava.  Basalt has low viscosity; it flows like water, meaning the flows are usually fairly thin, though they can "pond" in low-lying areas.  As the lava cools, it contracts and fractures into the hexagonal columns that make up the Causeway.  These columns are one of the distinguishing features of basalt flows all over the world, earning the moniker "columnar basalt".
The columns at the Giants Causeway have been eroded down over time, resulting in the famous stair-step appearance.
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #14 on: 27/03/2008 00:01:28 »
How come it's not all flat though?

Thank you for your answer!
 

Offline Bass

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The Giant's Causeway!! How was this formed?
« Reply #15 on: 27/03/2008 00:12:18 »
There are small differences in each column (size, fractures, surface area, inclusions, etc), so each will erode slightly differently.
 

Offline Karen W.

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The Giant's Causeway!! How was this formed?
« Reply #16 on: 27/03/2008 00:32:31 »
Cool I wondered if it was volcanic origins..! Thanks Bass!
 

Offline JimBob

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The Giant's Causeway!! How was this formed?
« Reply #17 on: 27/03/2008 02:52:04 »
My bad.. I think it's more pentagonal ;)

No you didn't do a bad - it is hexagonal if the cooling was even - the pentagonal shape is due to uneven cooling. It is the result of three - I think - basalt flows that have cooled.

Didn't read ALL of this until I answered. Bass and I differ but then all geologist fight amongst themselves, we are taught how to do this in school.

And I check it is three basalt flows, the step-way down is probably because the eruption occurred inland and the basalt flows thinned as they went out to sea. It could also be because they stayed the same thickness and were flowing downhill.


« Last Edit: 27/03/2008 02:57:19 by JimBob »
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #18 on: 27/03/2008 10:35:53 »
Sorry.. But what is a Basalt Flow?
 

Offline JimBob

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The Giant's Causeway!! How was this formed?
« Reply #19 on: 27/03/2008 12:09:43 »
Sorry.. But what is a Basalt Flow?

A volcano erupts. Lava flows down its sides. This lava is called basalt if it is rich in iron and magnesium. If the lava has a different chemical composition, it is called a rhyolite.
 

Offline Bass

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The Giant's Causeway!! How was this formed?
« Reply #20 on: 27/03/2008 20:15:42 »
To add to JimBob's last post..
Basalt and rhyolite are end members of the volcanic spectrum. 
Basalt probably originates in the mantle- it is relatively heavy, contains Fe and Mg silicate minerals, is dark colored, and flows easily (rarely explosive).  Think Iceland or Hawaii. (the ocean floor bedrock is basalt- covered by sediment)
Rhyolite is created when crustal rocks melt, are relatively light, contains K and Na silicate minerals, commonly light colored, and are high viscosity- they don't flow well or very far.  Continental crust is made of rhyolite and granite (the intrusive equivilent)- which is why the "lighter" continents float over the top of oceanic material at subduction zones.
The "steps" at the Giant's Causeway are all part of a single lava flow, additional basalt flows can be seen in the picture- the cliffs above the steps.  If the "steps" were made from more than one flow, there would be a distinct break between the columns.  As each lava flow cools, the tops and bottoms cool too quickly to form columns, the columns are formed in the more slowly cooled interior parts of the flow.
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #21 on: 27/03/2008 22:43:56 »
Coool!!
So is that mountain in the back of the picture like once a volcano?
 

Offline Bass

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The Giant's Causeway!! How was this formed?
« Reply #22 on: 27/03/2008 23:14:25 »
Not exactly
Better put, it was once covered by lava flows.  Basalt can flow for miles, so the volcano (or volcanic vent) could be quite a distance away.
« Last Edit: 27/03/2008 23:39:20 by Bass »
 

Offline Seany

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The Giant's Causeway!! How was this formed?
« Reply #23 on: 27/03/2008 23:15:45 »
So how come it's just this area bit that is like this, not the whole place the volcano's stuff flowed on?
 

Offline Bass

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The Giant's Causeway!! How was this formed?
« Reply #24 on: 27/03/2008 23:40:21 »
For some reason the columns are extremely well formed here- could be that the flow was slightly thicker, or cooling was a bit slower, or some other internal mechanism of that particular flow.  Then the erosion had to be just right- which probably was heavily influenced by its position in the tidal zones at sea level and the configuration of the coast.
 

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The Giant's Causeway!! How was this formed?
« Reply #24 on: 27/03/2008 23:40:21 »

 

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