1. Earth Structure & Plate Tectonics Notes
Goal 7 - Earth on the Move
Earth Structure & Plate Tectonics Notes

2. Earth, Inside & Out The Earth is divided into three layers Crust
Mantle
Core

3. 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.

4. And what type of crust would you like with your Earth?
There are two types of crust

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
Baker 7th grade science

6. (i) Oceanic Crust 1. Makes up the ocean floor
2.     Contains the dense rocks such as basalt
Thinner than the continental crust

7. 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

8. 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.

9. 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

10. (a) Asthenosphere Hot, weak zone directly under the lithosphere
Flows at a very slow rate

11. 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

12. The core is made of two layers
(1)  Outer core: molten & is responsible for the Earth’s magnetic field.
Inner core: solid