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Plate Boundaries. Why Plates move: . Convection!!!. Types of Plate Boundaries. Convergent Boundaries: Oceanic Crust subducts under Continental Crust Oceanic Crust subducts under Oceanic Crust Continental Crust collides with Continental Crust Divergent Boundaries Transform Boundaries.
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Why Plates move: • Convection!!!
Types of Plate Boundaries • Convergent Boundaries: • Oceanic Crust subducts under Continental Crust • Oceanic Crust subducts under Oceanic Crust • Continental Crust collides with Continental Crust • Divergent Boundaries • Transform Boundaries
Oceanic Crust Subducts under Continental Crust • What’s happening: • Plates are coming together. • The denser, heavier oceanic plate is subducting underneath the less dense continental crust. • Characteristics: • Volcanoes form inland from continental coastline. • Composite Cone Volcano and Cinder Cone eruptions. Very explosive and dangerous. • Deep Earthquake activity • Trench at the Subduction area. • Example: Cascade Mountain range on West Coast of US
Oceanic Crust Subducts under Oceanic Crust • What’s Happening: • Plates are coming together • One oceanic plate subducts under the other • Characteristics • Trenches at the subduction area • Earthquake activity • Shield Volcano eruptions • Example: Japan
Continental Crust Collides with Continental Crust • What’s happening: • Plates are coming together • No subduction! The two plates collide, the crust buckles, raising the elevation of the surrounding areas. • Characteristics • Mountains, not volcanic • Some earthquake activity • Example: • Himalayan Mountains
Divergent Boundaries • What is happening: • Plates are spreading apart • Typically found in oceanic crust • Characteristics: • Long crack in the crust, offset by a series of transform faults on both sides of the rift • Basaltic eruptions • Submarine mountain chain on the ocean floor • Shallow Earthquakes
Transform Faults • What’s happening: • Plates are sliding horizontally past each other as the two plates move in opposite directions • Characteristics: • Earthquakes! Plates may lock then suddenly move resulting in major earthquake activity • No volcanic activity
Hotspots- No interaction between two plates • What’s happening: • Hot spot activity occurs within one single plate due to unusually high temperatures in the mantle at that location. • The plate moves over a stationary mantle hot spot • Most common under oceanic crust except for Yellowstone National Park
Hot spots • Characteristic Features: • Chain of volcanoes forms as the plate continues to move over the hot spot • Shield Volcanoes • Quiet eruptions • Submarine seamounts, volcanoes in the chain that never reached sea level are common on the ocean floor
Pop Quiz: 1. Name the three major types of plate boundaries 2. Describe the main characteristics of each: 3. What type of boundary would I need to be at to find volcanoes? 4. What type of boundary would I find in the middle of the Atlantic Ocean? 5. What is formed from a hot spot?