Passage - General Questions

[tetsuya0129]

Hi Powerscore Staff,

I had trouble understanding the argument in Line 34 - 40. First, I don't understand why continental rocks of the same age could have different magnetic fields. If two rocks are of the same age, then they both created at the same time, and hence the same magnetic field, I suppose.

And, how does the fact of different magnetic fields help explain continents indeed drifted? I thought even though the new oceanic plate was indeed proved and thus has spread, but this does not prove anything about the continental plate.

I would really appreciate any help!

Leon

[Rachael Wilkenfeld]

Hi Leon,

The key here is that the rocks formed at the same time in two different places would both be pointing to the same magnetic north, but would be doing so from different angles. Picture a globe with a pin on top for magnetic north. Then picture two arrows, one on Maine, and one on Finland, both of which point at the magnetic north. Those arrows would be positioned differently, even though they are pointing to the same spot. This is because their starting point is different. They have to go on different paths to get to the magnetic north.

That's what we can see when we look at the rocks from North America and Europe. They don't point in an expected direction based on their current locations. But if we consider continental drift, they point to the same magnetic north. Based on the argument, we can see that the alignment of the rock to the magnetic field shows that the rocks were in different locations when they were originally formed.

Hope that helps.

[tetsuya0129]

Yes, this cleared things up for me. Thank you so much!