IMG_0875.jpeg

# Plate Tectonics Study Guide **Name:** Evan Hoffman **Date:** **Hour:** ## 1. Describe the theory of plate tectonics. Plate tectonics is the theory that the Earth's lithosphere is divided into several large plates that move slowly over the asthenosphere. ## 2. List and describe six pieces of...

# Plate Tectonics Study Guide **Name:** Evan Hoffman **Date:** **Hour:** ## 1. Describe the theory of plate tectonics. Plate tectonics is the theory that the Earth's lithosphere is divided into several large plates that move slowly over the asthenosphere. ## 2. List and describe six pieces of evidence that support the theory of plate tectonics. 1. **Earthquakes:** Earthquakes occur where tectonic plates meet. 2. **Mid-Ocean Ridges:** These ridges are locations where seafloor spreading occurs. 3. **Fossils:** The distribution of fossils across continents suggests they were once connected. 4. **Rock types:** Similar rock formations and sequences on different continents suggest they were once connected. 5. **Ancient climates:** Ancient climate patterns show that the continents were once positioned differently. This helps understand plate movements. 6. **Landforms:** Similar mountain ranges on different continents demonstrate they were once connected. ## 3. Explain why Wegener's theory of Continental Drift was not originally accepted. Wegener's theory lacked a mechanism for continental movement, and the explanation for the movement of continents was not convincing at the time to the scientific community. # 4. Describe the evidence that supports seafloor spreading. Magnetic striping (reversals of the Earth's magnetic field) in the seafloor provides evidence for seafloor spreading. Measuring the characteristics of the ocean floor, such as magnetic anomalies in the basaltic rocks, helps determine the spreading rate and direction of plates. ## 5. Describe the process of seafloor spreading. 1. The Earth's core heats magma from below. 2. Heated magma rises through convection currents. 3. Magma erupts at mid-ocean ridges; 4. The erupted magma cools and hardens. 5. The seafloor spreads apart at the ridges pushing older plates outward to form new seafloor. This creates new crust. ## 6. Use the following terms to explain what causes plate tectonics: density, temperature, convection, crust, core, movement, magma The Earth's core is hot. The hot core heats the mantle causing convection currents. The Earth's crust has different densities and temperatures and the differences in density and temperature in the mantle cause the plates to move. Magma (molten rock) from the mantle rises and cools to create new crust at mid-ocean ridges. When the plates are heated, they become more buoyant and rise. When they cool, they become dense and sink again. This constant movement creates plate tectonics. The different layers' density differences cause changes in the earth's plates causing movement.