1. Earth’s Changing Structures
SSA Review 5 –
Earth’s Changing Structures

2. Earth’s Interior Layer Depth Temp Description Crust 3 – 25 miles
Solid rock, covered with land and oceans.
Up to 230° F

3. Earth’s Interior Layer Depth Temp Description Mantle
Goes down to 1,800 miles
From 230° to 4400° F
Made of rock material
Lithosphere * top part ( miles) * solid rock * combines with the crust
Asthenosphere * below the lithosphere * miles below the Earth’s surface *hot, melted rock (magma)

4. Convection in the Earth’s Mantle

5. Earth’s Interior Layer Depth Temp Description Core
Goes down to 3,900 miles
4,400 to 10,000°F
Made of metal: nickel and iron.
Outer core * 1,800-3,100 miles below Earth’s surface *liquid metal
As hot as the sun
Inner core *3, miles below Earth’s surface *solid ball of metal *very high pressure

6. Mid-ocean Ridge – an underwater chain of mountains along the ocean floor.
*35,000 miles long

7. Sea-floor spreading: at the mid-ocean ridge, magma rises from the mantle and erupts.
The lava spreads out, pushing older seafloor away from the ridge, adding new rock material to the ocean floor.

8. Subduction - The process where the ocean floor sinks into a trench and down into the mantle.
Ocean trench - An underwater canyon that forms where the Oceanic crust sinks downward.

9. Plate Boundaries – the cracks that separate the Earth’s tectonic plates
Juan de Fuca Plate
Phillipine Plate
Cocos Plate

10. Types of Plate Boundaries
Name
Description
Two plates sliding past one another at a fault ( a crack in the Earth’s crust.)
1-Transform
*Earthquakes occur along these boundaries.

11. Rift valleys form at divergent boundaries on land.
Description
Name
2 - Divergent
Two plates moving apart from one another.
*Divergent boundaries in the ocean occur at the mid-ocean ridge. (Sea-floor Spreading)
Rift valleys form at divergent boundaries on land.

12. Description Name 3 - Convergent
Two plates moving into one another.
*Oceanic plates sink into a trench. Most volcanoes form here.

13. Name
Description
Two plates moving into one another.
Convergent
*Mountains form when two continental plates collide and the land pushes upward.