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G10 Science Q1-W4-5- Tectonic Boundaries.pptx
- 1. THE THEORY OF PLATE TECTONICS’ - BOUNDARIES, STRESSES, AND FAULTS
- 2. S10ES – Ia-j-36.3 Explain the different processes that occur along the plate boundaries
- 3. 1. WHAT IS THE THEORY OF PLATE TECTONICS? 2. WHAT ARE THE THREE TYPES OF PLATE BOUNDARIES?
- 4. WHAT ARE PLATES? • The Earth’s crust and upper mantle (Lithosphere) are broken into sections called plates A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust. Plates move around on top of the mantle like rafts
- 5. WHAT IS THE THEORY OF PLATE TECTONICS? The theory that pieces of Earth’s lithosphere are in constant motion, driven by convection currents in the mantle. • Plates move slowly in different directions ❑Cause different geologic events (like earthquake, volcano, etc.)
- 6. WHAT MAKES THE PLATES MOVE? Convection Currents in the mantle move the plates as the core heats the slowly-flowing asthenosphere (the elastic/plastic-like part of the mantle).
- 8. FAULT – BREAKS IN EARTH’S CRUST WHERE ROCKS HAVE SLIPPED PAST EACH OTHER. The edges of Earth’s plates meet at plate boundaries. ❖Extended deep into the lithosphere THERE ARE THREE TYPES OF PLATE BOUNDARIES! Plate Boundaries
- 9. WHAT ARE THE THREE TYPES OF BOUNDARIES? • Divergent Boundaries • Convergent Boundaries • Transform Boundaries A different type of plate movement occurs along each type of boundary.
- 10. DIVERGENT BOUNDARIES A plate boundary where two plates move away from each other. 🡨 🡪 RIFTING causes SEAFLOOR SPREADING
- 11. HOW IS THE ROCK PULLED AT DIVERGENT BOUNDARIES? ROCK GETS THIN IN THE MIDDLE AS IT IS PULLED APART. THIS STRESS IS CALLED
- 12. WHAT HAPPENS WHEN THE ROCK SNAPS FROM THE STRESS OF TENSION? A NORMAL FAULT (FAULT IS A BREAK IN EARTH’S CRUST) ROCK DROPS DOWN AS IT BREAKS
- 13. WHAT HAPPENS NEXT AT DIVERGENT BOUNDARIES? • A geologic feature or event… May form RIFT VALLEYS on continents SEA-FLOOR SPREADING in the ocean
- 14. HELPFUL HINTS… • Divergent is like “dissecting” or “dividing” • If you pull warm bubble gum or silly putty, it will thin in the middle until it is stressed so much that it breaks. • Happens on land & under H2O
- 15. FEATURES OF DIVERGENT BOUNDARIES • Mid-ocean ridges • rift valleys • fissure volcanoes
- 16. HOW IS THE ROCK PUSHED AT CONVERGENT BOUNDARIES? A plate boundary where two plates move towards each other. Boundaries between two plates that are colliding 🡪 🡨 This stress is called COMPRESSION
- 17. CONVERGENT BOUNDARIES • Places where plates crash (or crunch) together or subduct (one sinks under)
- 18. THERE ARE 3 TYPES OF CONVERGENT BOUNDARIES… Type 1 Ocean plate colliding with a less dense continental plate Subduction Zone: The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.
- 19. THERE ARE 3 TYPES OF CONVERGENT BOUNDARIES… Type 1
- 20. What else happens at Convergent Boundaries? VOLCANOES occur at subduction zones
- 21. ANDES MOUNTAINS, SOUTH AMERICA
- 22. TYPE 2 • Ocean plate colliding with another ocean plate • The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH
- 24. TYPE 3 • A continental plate colliding with another continental plate • Have Collision Zones: • A place where folded and thrust faulted mountains form.
- 25. • May form Mountain Ranges. These are Folded Mountains, like the Himalayas or the Rockies.
- 26. WHAT HAPPENS WHEN THE ROCK IS SQUEEZED FROM THE STRESS OF COMPRESSION? •A REVERSE FAULT •Rock is forced upward as it is squeezed.
- 27. HELPFUL HINTS… • Convergent = “Connecting” boundaries • May work like a trash compactor smashing rock. • Rock goes crunches up to make folded mountains. • Rock goes down “under” @ subduction zone.
- 28. TRANSFORM BOUNDARIES A plate boundary where two plates move past each other in opposite direction.
- 29. HOW IS THE ROCK BROKEN AT TRANSFORM BOUNDARIES? • Rock is pushed in two opposite directions (or sideways, but no rock is lost) • This stress is called SHEARING
- 30. WHAT HAPPENS NEXT AT TRANSFORM BOUNDARIES? • May cause Earthquakes when the rock snaps from the pressure. • A famous fault @ a Transform Boundary is the San Andreas Fault in California.
- 31. SAN ANDREAS FAULT, CA
- 32. WHAT HAPPENS WHEN THE ROCK IS SHEARED (OR “CUT”) FROM THE STRESS OF SHEARING? •A STRIKE-SLIP FAULT •Rocks on each side of the fault slip past each other as they break.
- 33. HELPFUL HINTS… • Shearing means cutting (“Shears” are like scissors) • Transform boundaries run like trains going past each other in different directions & they shake the ground!
- 34. Can you match the boundary name correctly with its diagram? A._____________ B._____________ C._____________ PLATE BOUNDARIES:
- 36. • Content, images, text, etc. used belong to the rightful owner. No copyright infringement intended.