Magnetic patterns: ocean floor pattern plotting Learning objectives:

 the Earth’s magnetic field has ‘flipped’ (the N pole becoming the S pole, and vice versa) many times over geological time as tectonic plates move apart, new rock is formed and locks in the direction of the magnetic field at the time Timing: about 20 minutes Introduction: Students use magnetic field data and a map of the ocean floor around Iceland to observe how the direction of magnetisation of the ocean floor varies. This links the magnetization of rocks with the theory of tectonic plates. Students tackle the worksheet Magnetic patterns: ocean floor pattern plotting. There are two closely related activities which teachers might wish to tackle at the same time. These are: Magnetic stripes on the ocean floor: a lab simulation: teacher demonstration The plate tectonic story: a scientific jigsaw: comprehension exercise