Palaeomagnetism Flashcards Preview

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Flashcards in Palaeomagnetism Deck (8)
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1
Q

What is every palaeomagnetism?

A

The study of the history of the Earth’s magnetic field

2
Q

What happens every 200,000 years to the Earth’s magnetic polarity?

A

It reverses polarity (magnetic north and south poles switch)

3
Q

What has palaeomagnetism provided evidence for?

A

The process of sea floor spreading

4
Q

What happens as magma erupts from mid-ocean ridges?

A

The magnetic minerals in the molten rock align themselves with the direction of the Earth’s magnetic field

5
Q

What happens to the magnetic alignment when the crust solidifies?

A

The alignment becomes fixed

6
Q

What is the difference between magnetic minerals aligned in periods of normal polarity and reverse polarity?

A

Normal polarity - magnetic minerals are aligned magnetic north near the North Pole
Reverse polarity - magnetic minerals are aligned magnetic north near the South Pole
Magnetic minerals are aligned in opposite directions to each other

7
Q

What does palaeomagnetism result in?

A

A series of alternating magnetic stripes along the sea floor.

8
Q

What do the strips on the sea floor show?

A

The crust is older the further away from a mid-ocean ridge you go - so the plates are moving apart