Chapter 11 Plate Tectonics

Continental Drift Continental Drift – a hypothesis proposed by Alfred Wegener, which states that continents have moved horizontally around the globe, over time, to reach their current locations. Pangea – the name Alfred Wegener gave to the large landmass, made up of all the continents, that he believed existed before it broke apart to form the present continents.

Evidence Supporting Continental Drift Climate CluesRock CluesFossil Clues Fossils of warm weather plants found in typically cold climates, Antarctica could have been closer to the equator at Pangaea time Similar rock structures on different continents, East coast of South America and West Coast of Africa Fossil remains found on different continents, dinosaurs could not swim across the ocean, ex. Mesosaurus

Seafloor Spreading Seafloor spreading – the theory that magma from Earth’s mantle rises to the surface at mid-ocean ridges and cools to form new seafloor, which new magma slowly pushes away from the ridge.

Evidence of Seafloor Spreading Magnetometer – a sensitive instrument that records magnetic data and is used to study Earth’s magnetic field. – Detects magnetic reversal – Alignment of rock reverses back and forth in strips parallel to the mid-ocean ridge.

Evidence of Seafloor Spreading Age Evidence – younger rocks are located at the mid-ocean ridges, older rocks are farther from the ridges on both sides.