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Grade 4 C-1 Sci. Def
Chapter 1 Earthquakes and Volcanoes
| Term | Definition |
|---|---|
| crust | Earth's outer layer; includes the rock of the ocean floor and large areas of land |
| mantle | The thickest layer of Earth; found just below the crust |
| core | The dense center of Earth; a ball made mostly of two metals, iron and nickel |
| plate | Continent-sized slab of Earth's crust and upper mantle |
| earthquake | A vibration, or shaking, of Earth's crust |
| fault | A break in Earth's crust along which rocks move |
| focus | The point underground where the movement of an earthquake first took place |
| epicenter | The point on the surface of Earth that is right above the focus of an earthquake |
| seismograph | An instrument that records earthquake waves |
| volcano | A mountain that forms when red-hot melted rock flows through a crack onto Earth's surface |
| magma | Melted rock inside Earth |
| lava | A melted rock that reaches Earth's surface |
| vent | The rocky tube in a volcano through which magma rises toward the surface |
| magma chamber | An underground pool below a volcano that holds magma |
| crater | A large basin formed at the top of a volcano when it falls in on itself |