1. Testing Plate Tectonics 9.4

2. Paleomagnetism
• The study of changes in Earth’s magnetic
field, as shown by patterns of magnetism
in rocks that have formed overtime.

3. Normal Polarity
• A magnetic field that is the same as that
which exists in the present.

4. Reverse Polarity
• A magnetic field opposite to that which
exists at present.

5. Hot Spot
• A concentration of heat in the mantle
capable of producing magma; which rises
to Earth’s surface.

6. Key Concept
• What evidence supports the theory
of plate tectonics?
–Continental drift, seafloor spreading,
palemagnetism, earthquake patterns,
ocean drilling, and ocean hot spots.

7. Key Concept
• How does paleomagnetism support
the theory of plate tectonics?
–By showing how Earth’s magnetic field
affects rocks overtime.