Plate Tectonics C hapter 7

1. Plate Tectonics Chapter 7

2. Inside the Earth section 1

3. The Composition of the Earth The Earth is divided into 3 layers They are the crust, mantle and core Each layer is made different materials that have different properties Scientists call these physical and chemical properties Layers are divided by the compounds that make them up compound is a substance made of 2 or more elements l

5. Less dense compounds make up the crust The densest compounds make the core heavier materials are pulled down by gravity

6. The Crust outer most layer 5 - 100 km thick thinnest of the 3 layers 2 types of crust continental oceanic both are made of oxygen, silicon and aluminum oceanic crust also has large amounts of iron, calcium and magnesium (denser materals)

7. The Mantle layer between the crust and the core thicker than the crust contains most of the Earth's mass never been visited because crust is too thick scientists information comes from observations made on the surface in some places mantle rock pushes to the surface and scientists can study it

8. One place scientists look for clues about the mantle is the ocean floor magma flows out of active volcanoes underwater volcanoes give clues about the composition of the mantle ex. magma has more magnesium and less aluminum and silicon the mantle is denser

9. The Core layer that extends below the mantle to the center of the Earth scientists think that the core is made of mostly iron with small amounts of nickle almost no oxygen, silicon aluminum or magnesium core makes up 1/3 of the mass of the Earth

10. The Physical Structure of the Earth The Earth is divided into 5 physical layers lithosphere asthenosphere mesosphere outer core inner core

13. Tectonic Plates Pieces of the lithosphere that move around on top of the asthenosphere are called tectonic plates

15. A Giant Jigsaw Puzzle All the tectonic plates have names Fit together with the plates around it Not all the plates are same size Some have oceans Some have continents Some have both oceans and continents

16. A Tectonic Plate Close- Up Plates contain both crust and mantle Tectonic plates float on the asthenosphere

17. Mapping the Earth's Interior How do scientists know things about the deepest parts of the Earth, where no one has ever been? Earthquakes vibrations called seismic waves are produced their speed depends on the density of the material they travel through ex. seismic waves traveling through a solid will go faster than traveling through a liquid

18. When earthquakes happen, machines called seismographs measure the times at which seismic waves arrive at different distances from the earthquake. Scientists can use the distance and the time it took to travel to determine the thickness of each layer of the Earth