1. Earth Structure & Plate Tectonics Notes
Earth on the Move
Earth Structure & Plate Tectonics Notes
Baker 7th grade science

2. Baker 7th grade science 2003-2004
Earth, Inside & Out
The Earth is divided into three layers
Crust
Mantle
Core
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3. Baker 7th grade science 2003-2004
Crust
(1)  This is the outermost layer of the Earth.
(2) This is the layer we walk on.
(3) It is a thick, rocky skin.
(4) If we think of the Earth as a billiard ball, this crust is as thin as a postage stamp stuck on a billiard ball.
(5) At its thickest, which is under mountain ranges, the crust is only about 35km (22mi) thick.
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4. And what type of crust would you like with your Earth?
There are two types of crust
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5. Baker 7th grade science 2003-2004
Continental Crust:
1. Makes up the continents
2. Contains light colored rocks such as granite.
3. Floats high on the mantle
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6. Baker 7th grade science 2003-2004
(i)    Oceanic Crust
1.       Makes up the ocean floor
2.     Contains the dense rocks such as basalt
Thinner than the continental crust
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7. Baker 7th grade science 2003-2004
Mantle
(1)  Hotter and denser than the crust because the deeper you go inside the earth, the temperature & pressure increases.
(2) Made of solid rock.
The Mantle is made of two zones
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8. Baker 7th grade science 2003-2004
Mantle Zones
(a)  Lithosphere
(i)    Thin, uppermost part of the mantle; cooler & less rigid
(ii) Floats on the athenosphere, and slides around very slowly.
(iii)  The upper part of the lithosphere melts rocks, forming a substance called magma.
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9. Baker 7th grade science 2003-2004
Magma
1.  Magma (melted rock) moves like hot oatmeal.
Uneven heating causes material in the mantle to constantly and slowly rise & fall in convection currents.
Convection Current: process by which hot fluid rises to the surface, and then sinks again, like soup being heated in a saucepan
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10. Baker 7th grade science 2003-2004
(a)  Asthenosphere
Hot, weak zone directly under the lithosphere
Flows at a very slow rate
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11. Baker 7th grade science 2003-2004
Core
i)       Deep within the Earth is the core
ii)    The core is made mostly of nickel & iron
iii)  Twice as dense as the mantle.
Main source of heat that triggers the convection currents
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12. The core is made of two layers
(1)  Outer core: molten & is responsible for the Earth’s magnetic field.
Inner core: solid
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