1. Standards:
3a. Know features of the ocean floor (magnetic patterns, age, and sea floor topography) provide evidence of plate tectonics. 3b. Know the principal structures that form at the 3 different kinds of plate boundaries. 3d. Know why & how earthquakes occur & the scales used to measure their intensity & magnitude. 3e. Know there are 2 kinds of volcanoes: 1 with violent eruptions producing steep slopes & 1 with voluminous lava flows producing gentle slopes. 3c. Know how to explain the properties of rocks based on the physical & chemical conditions in which they formed, including plate tectonic processes.

2. Earth’s Interior & Plate Tectonics

3. Earth’s Layers CRUST – topmost layer made of hard, solid rock.
Continental Crust – less dense & thicker
Oceanic Crust – more dense & thinner

4. Earth’s Layers MANTLE – layer beneath the crust
Makes up about 80% of Earth’s volume
Inside is “plastic” – it’s soft and deforms easily (like gum)

5. Lithosphere
The crust & upper part of the mantle
About 100 km thick

6. Asthenosphere
Layer of mantle below the lithosphere that consists of slowly flowing solid rock

7. Earth’s Layers CORE – Center of Earth composed of Iron & Nickel
Outer Core – liquid metal
Inner Core – solid metal

8. Alfred Wegener South America & Africa fit together.
Found fossils of the same organisms on both continents
Ignored, how did continents move?

9. Plate Tectonics
Lithosphere is made of 7 large pieces and many smaller pieces called tectonic plates
These plates fit together like a jigsaw puzzle and move in relation to one another

10. Plate Movement Plates move due to CONVECTION in the asthenosphere
As rock gets hot it is less dense and moves up, as it cools off it becomes more dense and falls
Like a lava lamp!

11. DIVERGENT PLATE BOUNDARIES
Two plates are moving APART
Causes magma to rise and cool, forming more lithospheric rock

12. Mid-Oceanic Ridges Mountain ranges that form at divergent boundaries
Called Ridges
Example: Mid-Atlantic Ridge

13. CONVERGENT PLATE BOUNDARIES
Two plates move towards each other
CONTINENTAL – CONTINENTAL PLATES
Creates MOUNTAINS
Appalachians (old)
Himalyas (young)

14. SUBDUCTION ZONES OCEANIC – CONTINENTAL PLATES
SUBDUCTION = denser plate goes under less dense plate
Dense plate is destroyed & the magma rises to create volcanic island arcs
The subducting plate also creates a trench

15. Examples: Aleutian Islands & Japan

16. TRANSFORM FAULT BOUNDARIES
Two plates break and scrape past one another
Cracks where they move are called faults
Cause earthquakes
Ex: SAN ANDRES FAULT

17. Evidence for Plate Tectonics
MAGNETIC PATTERNS
There are “bands” of rock on the ocean floor with alternating magnetic polarities
Earth’s magnetic field reverses (200,000 yrs)