Helps explain how continents moved apart (C.S.

 In WWI German scientists used sound waves to detect submarines on the seafloor

 In 1960 a Princeton University scientist suggest the idea of seafloor spreading  That hot, less dense material below Earth’s crust rises to the surface at mid-ocean ridges

 In 1968, the Glomar Challenger was sent with a drilling rig to obtain rock samples on the seafloor

 At these mid-ocean ridges there is a temperature increase that bring heat and chemicals to the center of these ridges  Gigantic clams, mussels and tube worms live there because it is so warm

 Earth has a magnetic field  A north pole  A south pole Magnetic lines, or directions, of force leave Earth near the south pole and enter Earth near the north pole

 Several times in history, Earth has had a magnetic reversal  Every 1000 years or so  Recorded in the rocks forming near mid-ocean ridges

 Magnetite is an iron bearing mineral  So what do we know about iron magnets?  These minerals align themselves with earths magnetic field

These rocks that contain the magnetite prove that earth’s magnetic field has reversed This helps show how the crust can move

 Bozeman Plate Tectonics Video Bozeman Plate Tectonics Video