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1. Rock magnetism and plate motion: A volcanic rock collected from the 10 degree

ID: 112119 • Letter: 1

Question

1. Rock magnetism and plate motion: A volcanic rock collected from the 10 degrees north latitude is found to contain a “fossil” magnetic inclination of +45 degrees (positive counter-clockwise). Assuming that the earth’s magnetic field was normal polarity (i.e., the same as today), did this rock form in the northern or southern hemisphere? In one sentence, explain why.

2. What was the latitude of formation at the time this rock formed? How far did this rock travel in a north-south direction? Use the curve given in Lecture 4 (you can download this from blackboard).

Here is the curve:

90 80 70 60 50 40 O 30 20 10 0 10 20 30 40 50 60 70 80 90 7 Equator Pole Latitude

Explanation / Answer

Northen hemisphere. Because it is an normal polarity situation we can say that it would be southern if this is a case of reverse polarity but reverse polarty took time aeround 250000 years so its normal polarity .

Answer 2- in my concern it should be 25o north. Because of the magnetic inclination.

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