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Teaching the Theory of Pangea


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So, we covered the theory of Pangea (you know, where all the continents were together like puzzle pieces and then drifted apart) and I'm really not buying it. :confused: Is there really overwhelming evidence for this? I tend to think of the continents as shaped by sea level. I know there is tectonic plate movement, but...that dramatic?? :tongue_smilie:

 

Anyone teach this lately? We covered it in Apologia Science - it's in the zoology textbook (land animals).

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What are you basing your skepticism on?

 

I just did a quick calculation. Pangaea existed around 250,000,000 years ago. Europe and North America are moving apart at a rate of about 3 inches per year. That's about 12,000 miles in 250,000,000 years.

 

I guess I'm not understanding why you don't think Pangaea is in the realm of possibility given this amount of movement over the period of time in question.

Edited by EKS
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What are you basing your skepticism on?

 

I just did a quick calculation. Pangaea was around 250,000,000 years ago. Europe and North America are moving apart at a rate of about 3 inches per year. That's about 12,000 miles in 250,000,000 years.

 

I guess I'm not understanding why you don't think Pangaea is in the realm of possibility given this amount of movement over the period of time in question.

 

See, those calculations make it seem possible. I think I don't know enough about the theory to teach it and the textbook wasn't very convincing. I do find the fossil record to be very convincing. I guess I don't view continents as pieces.

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Right, there are tons of connection points for both rocks and fossils that indicate where continents were connected in past. Current sea floor spreading and the rifting of eastern Africa also provide examples of how movement is still occurring. We're talking about things that have happened over huge amounts of time, so the change is imperceptible over the course of human lifetimes....

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You can actually measure the continental drift - in Iceland, there is a fault that widens every year by several centimeters.

There is fossil evidence as well - similar plant fossils on different continents, Mesosaurus fossils in Brazil and South Africa.

There is continuity in glacial sediments.

The orientation of magnetic moments in minerals contain information about the earth's magnetic field and their position relative to the poles which can be traced - I am not familiar with the details, but googling paleomagnetism should give you more information.

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You can actually measure the continental drift - in Iceland, there is a fault that widens every year by several centimeters.

There is fossil evidence as well - similar plant fossils on different continents, Mesosaurus fossils in Brazil and South Africa.

There is continuity in glacial sediments.

The orientation of magnetic moments in minerals contain information about the earth's magnetic field and their position relative to the poles which can be traced - I am not familiar with the details, but googling paleomagnetism should give you more information.

 

Ok, I'm trying to remember from school. But isn't there a fault line in the Atlantic that is supposed to be responsible for north America/south America pushing away from Europe/Africa?

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Right, there are tons of connection points for both rocks and fossils that indicate where continents were connected in past. Current sea floor spreading and the rifting of eastern Africa also provide examples of how movement is still occurring. We're talking about things that have happened over huge amounts of time, so the change is imperceptible over the course of human lifetimes....

 

:iagree:

 

Although- the earthquake in Japan moved the country 8 inches.... in a few seconds. So while most movement is imperceptible over even thousands of years, there are some dramatic instances of noticeable movement.

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