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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 |