2-2-18 Evidence and Forces of Plate Tectonics

Do Now: Submit Lab Reports to the blue bins Do Now: Submit Lab Reports to the blue bins. Copy and fill in the blanks for the following statements. 1. The consists of the crust and the solid uppermost layer of mantle. 2. The is so hot that it behaves like a plastic material. 3. plate boundaries form where two plates collide. 4. plate boundaries form where two plates separate. 5. plate boundaries form where two plates slide horizontally past each other.

Do Now: Submit Lab Reports to the blue bins Do Now: Submit Lab Reports to the blue bins. Copy and fill in the blanks for the following statements. The consists of the crust and the solid uppermost layer of mantle. Lithosphere The is so hot that it behaves like a plastic material. asthenosphere _____plate boundaries form where two plates collide. convergent _____plate boundaries form where two plates separate. divergent ______plate boundaries form where two plates slide horizontally past each other. Transform

Evidence for Plate Tectonics

Evidence for Plate Tectonics Scientists can measure how fast continents move using a network of satellites called the Global Positioning System.

Evidence for Plate Tectonics Because plates are rigid, tectonic activity occurs where plates meet. Volcanoes form where plates separate along a mid-ocean ridge or continental rift or collide along a subduction zone. Mountains can form where two continents collide.

Turn & Talk: Discuss with your shoulder partner the following question. How are earthquakes and volcanoes related to the theory of plate tectonics? Most volcanic eruptions and earthquakes occur along plate boundaries.

Plate Motion EQ: Why do tectonic plates move?

Plate Motion Earth’s plates move because the asthenosphere moves underneath the lithosphere. Convection: the circulation of particles within a material caused by differences in thermal energy and density. Conveccion: circulacion de particulas en el interior de un material causada por diferencias en la energia termica y la densidad.

Plate Motion Hot mantle material rises upward and comes in contact with Earth’s crust. As the mantle cools, it becomes denser and then sinks, forming a convection current. Convection currents in the asthenosphere act like a conveyor belt moving the lithosphere above it.

Turn & Talk: Answer the following question with your shoulder partner. What causes convection? Differences in density and temperature

Plate Motion There are three forces that interact to cause plate motion: basal drag, ridge push, and slab pull. Basal drag refers to how convection currents in the asthenosphere circulate and drag the lithosphere like a conveyor belt moving items along at a supermarket checkout.

Plate Motion Rising mantle material at mid-ocean ridges creates the potential for plates to move away from the ridge with a force called ridge push: the process that results when magma rises at a mid-ocean ridge and pushes oceanic plates in two different directions away from the ridge. Empuje de dorsal: proceso que resulta cunado el magma se levanta en la dorsal oceanica y empuja las placas oceanicas en dos direcciones diferentes, lejos de la dorsal.

Plate Motion As a slab, or dense plate, sinks, it pulls on the rest of the plate with a force called slab pull: the process that results when a dense oceanic plate sinks beneath a more buoyant plate along a subduction zone, pulling the rest of the plate that trails behind it. Convergencia de placas: proceso que resulta cuando una placa oceanica dense se hunde debajo de una placa flotante en una zona de subduccion, arrastrando el resto de la placa destras suyo.

A Theory in Progress Plate tectonics has become the unifying theory of geology, but several unanswered questions remain. Why is Earth the only planet in the solar system that has plate tectonic activity? Why do some earthquakes and volcanoes occur far away from plate boundaries? What forces dominate plate motion? What will scientists study next? This is a 3-D image of seismic wave velocities from a new technique called anisotropy. This new technology might help scientists better understand the process that occur within the mantle and along plate boundaries.

Tectonic plates are made of cold and rigid slabs of rock. Mantle convection— the circulation of mantle material due to density differences—drives plate motion.

The three types of plate boundaries are divergent, convergent, and transform boundaries.

What word do geologists use to describe the forces that shape Earth’s surface? A. semiplastic B. lithosphere C. tectonic D. mantle

Which of these is made up of the crust and the solid, uppermost mantle? A. seafloor B. lithosphere C. biosphere D. hydrosphere

What type of boundary forms where two plates separate? A. convergent plate boundary B. transform plate boundary C. new plate boundary D. divergent plate boundary

5. Continents drift across a molten mantle. Do you agree or disagree? 5. Continents drift across a molten mantle. 6. Mountain ranges can form when continents collide.