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Vocabulary
- **Basalt**: a dark, dense rock with a fine texture (usually found in oceanic crust) - **Granite**: a rock that has larger crystals than **basalt** (usually found in continental crust) Inner** **core**: a dense ball of soled metal
 * Geologists**: scientist who study the forces that make and shape the Earth
 * Rock**: the material that forms most of the Earth's surface
 * Geology**: the study of Earth
 * Constructive forces**: forces that shape the surface by building up mountains and landmasses
 * Destructive forces**: forces that slowly wear away mountains and, eventually, every other feature on the surface
 * Continents**: the seven great landmasses on Earth
 * Seismic waves**: are produced when earthquakes occur
 * Pressure**: the pushing on a surface or area
 * Crust**: a layer of rock that forms Earth's outer skin
 * Mantle**: a layer of hot rock between the crust and above the core
 * Lithosphere**: a rigid layer that contains the **crust** and the uppermost part of the **mantle**
 * Asthenosphere**: a soft layer under the **lithosphere** ( the material can flow easily in this layer)
 * Outer core**: a layer of molten metal that surrounds the **inner core

The Science of Geology

 * studying surface changes
 * the surface is constantly changing
 * finding indirect evidence
 * we can't get to the middle of the Earth
 * instead of digging a hole we use seismic waves
 * Geologists record the **seismic waves** when an earthquake happens( they study the paths the waves take)

A Journey to the Center of the Earth

 * temperature changes
 * rocks are cool near the top
 * about 20 meters down, the rocks are getting warmer
 * the temperatures rises 1 Celsius ever 40 meters
 * that's pretty hot for the temperature down there
 * pressure also changes
 * as you go deeper the pressure increases

The Crust

 * There are two kinds of **crusts**
 * Oceanic Crust
 * the oceanic crust contains mostly **basalt**
 * darkly colored
 * Continental Crust
 * the continental crust contains mostly **granite**
 * lightly colored

The Mantle

 * the **lithosphere** contains part of the **mantle**
 * the **lithosphere** is about 100 kilometers thick
 * the **asthenosphere** is what the **lithosphere** floats on
 * the **asthenosphere** is the lowest part of the mantle

The Core

 * there are two parts that are called the "**core**"
 * The **Outer Core**
 * the **outer core** is a layer of molten metal
 * The **Inner Core**
 * extreme pressure squeezes the atoms of the iron so much they can't spread
 * the core makes about one third of Earth's mass but only 15 percent of its volume

Earth's Magnetic Field

 * the magnetic fields are created by the core
 * the inner core moves, this movement creates this field
 * the magnetic field causes the Earth to act like a big magnet bar
 * without the magnetic field, we would get burned from the sun's harmful rays (like the ultra violet rays)

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