1. Magnetic stripes on the Seafloor Part 1: Earth’s Magnetic field

2. Earth’s magnetic field is a Dipole Field, like a bar magnet’s field

3. North Geographic Pole: top of Earth, “true north” North Geomagnetic Pole: where your compass points

4. Rocks with iron in them got magnetized by Earth’s field! Paleomagnetism: studying the magnetization of old rocks What was Earth’s magnetic field in the past?

5. Earth’s field sometimes flips (Reverses)

6. Normal Polarity: Your compass points near geographic North, the same way it does today Reverse Polarity: Your compass points the opposite way it does today (near the South geographic pole)

7. Geomagnetic Polarity Time Scale (GPTS): Timeline of magnetic field polarity

8. VGP: Virtual Geomagnetic Pole Scientific name for the ancient geomagnetic north pole location (given in latitude and longitude) Important Review: POSITIVE Latitudes = Northern Hemisphere NEGATIVE Latitudes = Southern Hemisphere GPTS activity

9. Magnetic stripes on the Seafloor Part 2: The Seafloor Tape Recorder

10. Newly forming ocean crust gets magnetized “Stripes” of new crust are Normal and Reverse polarity Stripes are symmetrical on both sides of the mid-ocean ridge

11. Sea-floor Spreading and Magnetic Stripes