1. Tectonic Plates

2.  The LITHOSPHERE, or Earth’s outer layer, is broken up into huge pieces called _________ __________. –These plates are continuously ________.  Let’s look at pg. 396 tectonic plates moving

3. Answer this question…  How do we know so much about the mantle and the core? –Seismic waves, or vibrations produced from earthquakes, travel at different speeds through the Earth. Their speed depends on the density and composition of the material they pass through. –Traveling through a solid will go faster than through a liquid.

4. Restless Continents  Look at pg. 400!  In the early 1900s, ___________ ___________ wrote about his hypothesis of ____________ ______.  Continental drift = the _____________ once formed a single ______________, then broke up, and drifted to their current locations.  Continental drift also explained why __________ of the same plant and animal species are found on continents that are on different sides of the Atlantic Ocean. AlfredWegener continental drift continents landmass fossils

5. Pangaea  Wegener thought that all of the present continents were once __________ in a single, huge continent called ______________.  Pangaea is Greek for ______________. joined Pangaea “all earth”

7. Events caused by Earth’s plate movement: 1. Sea-floor spreading3. Earthquakes 2. Mountain building4. Volcanoes

8. Mountain Building  ______________ exist because tectonic plates are continually ______________ and ___________ with one another.  ________________ or ____________ can form mountains in several ways. Mountains moving colliding Compressiontension

9. 3 types of mountains: 1.Folded Mountains: --Form when rock layers are _______________ together and pushed ___________. --Example: Appalachian Mountains squeezed upward

10. 2. Fault-Block Mountains: --Form when tectonic forces put ___________on the Earth’s crust causing large blocks to_________ _________. --Example: Tetons in Wyoming tension dropdown

12. 3. Volcanic Mountains- --Form when _________ rises to the Earth’s surface and erupts. –Example: Mount St. Helens magma

13. Earthquakes  Most earthquakes take place near the edges of __________ ___________.  As tectonic plates push, pull, or slip past each other, stress increases along breaks in the Earth’s crust, or ___________.  In response to this stress, rock in the plates _______________.  __________ _______________: Imagine a stretched rubber band. You can only stretch rock so far before it breaks. When the rock breaks, it releases ________________. tectonic faults plates deforms Elasticdeformation energy

14. Sea-Floor Spreading  Process by which new oceanic ________________ forms as __________ rises toward the surface and solidifies.  Occurs at ____________ __________, or underwater mountain chains  As ___________ __________ move away from each other, the sea floor spreads apart and magma fills the gap. lithospheremagma mid-oceanridges tectonicplates

15. Look at page 402…  Figure 3: Sea-Floor Spreading

16. Volcanoes  Likely to form at _________ ______ _________.  ________ _________ _____ _________, plate boundaries surrounding the Pacific Ocean, contains nearly _____ of the world’s active volcanoes.  About _____ of active volcanoes on land form where plates ______________, and about ______ form where plates ____________.  At these plate boundaries it is possible for _____________ to form and travel to the surface. TheRingofFire 75% 15% 80% collide separate magma tectonicplateboundaries

17. The Ring of Fire

18. 3 Types of Boundaries…  Look at pg. 404-405

19. 1. Convergent Boundaries: --Formed when two tectonic plates __________ a. Continental-Continental Collisions b. Continental-Oceanic Collisions c. Oceanic-Oceanic Collisions COLLIDE

20. 2. Divergent Boundaries: --Formed when two tectonic plates ____________ SEPARATE

21. 3. Transform Boundaries: --Formed when two tectonic plates ________ past each other horizontally SLIDE