1. Plate Boundary Features
Food Tectonics

2. Dance of the Plate Boundaries

3. Food Tectonics
Spread frosting into a layer about one centimeter thick (to about the size of a deck of cards). The frosting in this model represents the asthenosphere, the plastic-like layer on which Earth's plates ride.
Tectonic plates are composed are made up of the lithosphere (which includes the crust and uppermost mantle)
Oceanic Lithosphere (which is thin and denser) is represented by a fruit roll up
Continental Lithosphere (which is thick, but less dense) is represented by graham crackers

4. DIVERGENT Boundaries TENSION FORCES CONSTRUCTIVE BOUNDARY:
New crust is created where plates diverge

5. Oceanic-Oceanic Divergent Boundary
Place the two squares of fruit roll up (oceanic plates) onto the frosting right next to each other (you may need to flatten them out a little bit)
Press down slowly on the fruit roll up squares (because they are dense and will sink a bit into the asthenosphere) as you slowly push them apart about 0.5 cm
Discuss your observations with your group

6. Mid-Ocean Ridge Type of Lithosphere Interaction
Oceanic-Oceanic
Description of Boundary Feature
Two oceanic plates RIFT (spread apart)
Magma rises through the crack and forms a volcanic mountain chain on both sides of the rift
A valley runs down the center of the MOR

7. Mid-ocean Ridges

8. Mid-Atlantic Ridge

9. Continental - Continental Divergent Boundary
Hold both ends of your candy bar and very slowly pull the candy bar apart.
Discuss your observations with your group

10. Rift Valley Type of Lithosphere Interaction
Continental-Continental
Description of Boundary Feature
Two continental plates RIFT (spread apart)
Long, faulted valleys result as earth’s lithosphere is ripped apart
Land breaks apart into distinct land masses and the surrounding water will fill the space between them

12. East African – Continental Rift Valley
Iceland – Continental Rift Valley

13. Convergent Boundaries
COMPRESSION FORCES
SUBDUCTION:
A denser plate plunges below a less dense plate through the asthenosphere and forms a trench

14. Continental-Oceanic Convergent Boundary
Remove one of the fruit roll up pieces from the frosting. (You can eat it if you wish!)
Place one of the graham cracker halves lightly onto the frosting asthenosphere next to the remaining fruit roll up piece. The graham cracker represents continental lithosphere, which is thicker and less dense than oceanic lithosphere. It floats high on the asthenosphere so don't push it down.
Gently push the continent (graham cracker) towards the ocean plate (airhead) until the two overlap and the graham cracker is on top. The oceanic plate subducts below the continental one.
Discuss your observations with your group.

15. Continental Volcanic Arc
Type of Lithosphere Interaction
Continental-Oceanic
Description of Boundary Feature
VOLCANIC MOUNTAIN RANGES
occur because friction melts the sinking plate and the magma rises to the surface to create a volcano
Earthquakes (shallow and deep) can also occur along the sinking plate due to friction

17. Real Life Example Arenal Volcano, Costa Rica

19. Continental-Continental Convergent Boundary
The next model is what happens when two continents collide. Remove both the cracker and fruit roll up from the frosting asthenosphere. (You can eat or discard the airhead)
Place one edge of both crackers into the glass of water for just a few seconds.
Place the crackers onto the frosting with wet edges next to each other.
Slowly push the wet graham cracker edges towards each other.
Discuss your observations with your group

20. Folded Mountains Type of Lithosphere Interaction
Continental-Continental
Description of Boundary Feature
Two continental plates run into one another
The plates resist downward motion because the continental rocks are relatively light/ low density
MOUNTAINS FORM because the crust tends to buckle and be pushed upward or sideways
Mostly shallow earthquakes will occur at these locations

23. Real Life Example Himalayan Mountains

24. Volcanic Island Arc Type of Lithosphere Interaction
Oceanic-Oceanic
Description of Boundary Feature
Two oceanic plates run into one another
One of the oceanic plates is more dense because it is older and is pulled below the other plate when they collide in a Subduction Zone (forms a trench)
Volcanic Island Arcs occur because oceanic crust melts as it goes deeper into the Earth. The newly-created magma rises to the surface and forms volcanoes
Earthquakes (shallow and deep) can also occur

26. Real Life Example Galapagos Islands

28. Japan

29. Ocean Trenches Type of Lithosphere Interaction
Continental-Oceanic
Oceanic-Oceanic
How does an Ocean Trench form?
Found where subduction is occurring; one plate collides with and slides beneath another plate

32. Transform Boundaries
SHEAR STRESS:

33. Transform Boundary
Pick the two crackers up off the frosting and turn them around so that two dry edges are next to each other.
Push one cracker past the other to simulate a transform plate boundary like the San Andreas fault!
Discuss your observations with your group

34. Fault Lines Type of Lithosphere Interaction
Continental-Continental
Oceanic-Oceanic
Description of Boundary Feature
Occurs when plates move past one another; rocks grind against one another, stress builds up and can deform lithosphere; rocks eventually break, release energy (earthquake)
On the ocean floor, transform boundaries cause mid-ocean ridges to be offset/ jagged

36. Real Life Example San Andreas Fault

40. Summary

42. Ring of Fire
Reading and discussion