1. Tectonic Plate Boundaries
Types of motion and effects

2. Transform Tectonic plates slide past each other
Results in linear fault valleys or undersea canyons
Grinding plates results in a wide boundary zone for earthquakes
No magma is formed, so crust is cracked and broken, not destroyed or created

4. i. Instead, linear valleys can mark the boundaries
ii. San Andreas Fault - moving northwards as rest of California moves southwards - at a rate of about 6cm each year

6. Convergent Tectonic plates colliding with each other
Collision causes one or both plate edges to buckle
i. Results in mountain ranges forming
ii. Sometimes trenches form from one plate sliding (subducting) under the other

8. B. Chain of volcanoes often forms parallel to the boundary, mountain range, and trench
C. Earthquakes can result
D. Subducting oceanic plates melt, causing magma to rise and form new continental crust made of granite

9. II. Himalaya Mountains
2,900km long between India and Tibet
Began forming million years ago when India and Eurasia, two separate land masses, collided
Still causes disastrous earthquakes today

11. III. Subducting Zones
When the older of two colliding oceanic plates is pushed under the younger one
i. Because older crust is more dense, meaning the younger one is pushed over the top of the older one
ii. Enters the asthenosphere

13. B. Can result in trenches as much as 70 miles wide, hundreds of miles long, and several miles deep
i. Marianas Trench, where the Pacific Plate is pushed under the Eurasian Plate
ii. Deepest sea floor in world - more than 36,000 feet below the surface

15. C. Trench-Flipping
i. Occurs when descending oceanic crust also carries a continent, which is less dense
ii. Continent dives into trench, following, until it becomes stuck

16. iii. Crust crumples into mountains, causing the leading edge of oceanic plate riding over the other plate to deposit some crust on top of the continent
iv. Pressure builds up until the oceanic crust eventually is forced under the continent, flipping the trench

17. Divergent Tectonic plates moving away from each other
Due to heat from radioactive decay in earth’s interior
Over convection currents
i. Lifts lithosphere

19. C. Stretches and breaks, sliding away
D. Divergent plate boundaries created due to heat from radioactive decay in earth’s interior
E. Results in creation of mid-oceanic ridges
i. Atlantic Ocean - 2cm per year

21. Mid-Oceanic Ridges Stretching of the lithosphere creates deep fissure
Pressure released upon breaking
i. Melted mantle/magma flows into fissure, where it solidifies and grows, pushing original broken crust further away upon creation of new crust

22. B. Typically 30-50km wide when on land, whereas on the ocean floor, rifts are no wider than 1km

23. C. Sea-floor spreading
i. Process of new crust being produced and attaching itself to trailing edge of plate as mid-ocean ridge is created
ii. Older crust is further from ridge
iii. Made of basalt

24. II. Underwater mountain range
Over 35,000 miles long
Over 12,000 feet high
Over 1,200 miles wide

25. Faults
Slight fractures in Earth’s crust caused by stretching and compression of plates
Two main types
Normal Faults: crust stretches to form a basin/range flanked by fault-block mountains
i. Southern Rocky Mountains

26. B. Reverse Fault: compression squeezes crust together as one block slides over another, creating overthrust mountains
i. Montana’s Glacier National Park

27. C. Lateral/Transform/Strike-Slip Faults:when fractures in the surface are vertical but result in mainly horizontal movement of the blocks and when plates grind, shear, slide past each other, causing earthquakes but not mountains
i. Found where significant movement occurs along a fracture in the crust

28. Earthquakes A perceptible shaking of Earth’s surface
Can be almost unfelt to so violent a whole city topples and people can be tossed about
Results from a sudden release of tension in Earth’s crust

29. II. Caused by seismic activity
Measured by a seismograph
i. Frequency, type, size
ii. Three depths: shallow-focus (less than 70km deep); mid-focus (70-300km deep); deep-focus ( km deep)

30. B. Origin called epicenter
C. Micro (less than 2.0), Minor ( ), Light ( ), Moderate ( ), Strong ( ), Major ( ), Great (8.0 and greater)
i Sri Lanka Tsunami ( ) is third largest measured; lasted mins

31. III. Comprised of:
Hanging Wall - block above fault plane
Footwall - block below fault plane
IV. Shapes:
Syncline - bend in the rock swooping downward
Anticline - bend in the rock rising upward like a hill