Magnetic Stripes on the Seafloor Part 1 Seafloor

Earth’s magnetic field is a Dipole Field, like a bar magnet’s field http: //earthref.

Earth’s field sometimes flips (Reverses) http: //earthref. org/SCC Scripps Classroom Connection

What was Earth’s magnetic field in the past? Rocks that cool from lava get

Normal Polarity: Your compass points near geographic North, the same way it does today

Timeline of magnetic field reversals Scientists found a striped “barcode” pattern like this on

Magnetic Reversals Timeline Activity “VGP Latitude”: The value scientists measure in the lab to

Magnetic Stripes on the Seafloor Part 2: The Seafloor Tape Recorder http: //earthref. org/SCC

Newly Forming Ocean Crust Gets Magnetized • “Stripes” of new crust are Normal and

Conclusions ● The Earth’s magnetic field switches throughout time! ● Rocks can record the

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Magnetic Stripes on the Seafloor Part 1: Seafloor Magnetic Stripes & Earth’s Magnetic field http: //earthref. org/SCC Scripps Classroom Connection

Earth’s magnetic field is a Dipole Field, like a bar magnet’s field http: //earthref. org/SCC Scripps Classroom Connection

Earth’s field sometimes flips (Reverses) http: //earthref. org/SCC Scripps Classroom Connection

What was Earth’s magnetic field in the past? Rocks that cool from lava get magnetized by Earth’s field! The magnetization direction 1) Depends on the direction of the magnetic field 2) Gets locked in when the rock cools below a certain temperature This is how the volcanic seafloor got its stripes! http: //earthref. org/SCC Scripps Classroom Connection

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) http: //earthref. org/SCC Scripps Classroom Connection

Timeline of magnetic field reversals Scientists found a striped “barcode” pattern like this on the seafloor! http: //earthref. org/SCC Scripps Classroom Connection

Magnetic Reversals Timeline Activity “VGP Latitude”: The value scientists measure in the lab to find out if a rock was formed during Normal or Reverse polarity (VGP: Virtual Geomagnetic Pole) VGP Latitude of YOUR rock sample: POSITIVE Latitudes = Northern Hemisphere = Normal NEGATIVE Latitudes = Southern Hemisphere = Reverse http: //earthref. org/SCC Scripps Classroom Connection

Magnetic Stripes on the Seafloor Part 2: The Seafloor Tape Recorder http: //earthref. org/SCC Scripps Classroom Connection

Newly Forming Ocean Crust Gets Magnetized • “Stripes” of new crust are Normal and Reverse polarity • Stripes are symmetrical on both sides of the midocean ridge http: //earthref. org/SCC Scripps Classroom Connection

Conclusions ● The Earth’s magnetic field switches throughout time! ● Rocks can record the magnetic field direction. ● The Magnetic Reversal Timescale. ●Seafloor Magnetic Stripes are Symmetrical! http: //earthref. org/SCC Scripps Classroom Connection