Presentation on theme: "The Theory of Plate Tectonics Concepts: What is the theory of plate tectonics? What are the three types of plate boundaries? Terms: J. Tuzo Wilson Plate."— Presentation transcript:
The Theory of Plate Tectonics Concepts: What is the theory of plate tectonics? What are the three types of plate boundaries? Terms: J. Tuzo Wilson Plate Scientific theory Plate tectonics Fault Divergent boundary Rift valley Convergent boundary Transform boundary
J. Tuzo Wilson and Plates A Canadian scientist, J. Tuzo Wilson, observed that there are cracks in the continent similar to those on the ocean floor. In 1965, Wilson proposed a new way of looking at these cracks. According to Wilson, the lithosphere is broken into separate sections called plates.
The Theory of Plate Tectonics The theory of plate tectonics explain the formation, movement, and subduction of Earth’s plates.
How do the plates move? The theory of plate tectonics states that pieces of Earth’s lithosphere are driven by convection currents in the mantle. As the plates move, they collide, pull apart, or grind past each other producing spectacular changes in Earth’s surface. Volcanoes, mountain ranges, and deep ocean trenches The plates move very slow about 1-24 centimeters a year. About as fast as your fingernails grow. They have been moving for tens of millions of years.
As we review each plate boundary, complete a tree map and include the following: Focus Questions: 1. Plate Boundary 2. Which direction are the plates moving at these boundaries in relationship to each other? 3. What action occur at each location/type of plate boundary? 4. What forms because of these actions? 1. Examples
Tree Map Plate Boundary Plate Movement Definition Action Examples Location Arrows
Types of plate boundaries Divergent plate boundary 1.Ocean: Mid Oceanic Ridge 2.Land: Continental Rift zone Convergent plate boundary 1.Oceanic-oceanic convergence – Subduction Trench 2.Continental-continental convergence – No Subduction - Mountains 3.Oceanic - continental convergence – Subduction Trench Transform plate boundary Earthquakes Crust is neither created nor destroyed.
Divergent plate boundaries A place where two plates move apart, or diverge
Ocean Mid-Ocean Ridge E.g. Mid-Atlantic ridge is a result of sea floor spreading new basaltic magma rises to the surface along the ridge forming new oceanic crust.
ThingvellirThingvellir Rift Valley Slicing through the center of Iceland is the Mid-Atlantic Ridge. This is the boundary between theNorth American and Eurasian tectonic platesMid-Atlantic RidgeNorth AmericanEurasian tectonic plates Thingvellir National ParkThingvellir National Park, in southwestern Iceland, is one of the few spots in the world where an underwater ridge rises above the water surface. Iceland is one of the most geologically active places on Earth with more than 15 volcanoes that have erupted in the last century.
Land Rift valleys may increase in size till water fills them to form a Sea The Red Sea and the Gulf of Aden were once rift valleys. These rift valleys often have volcanoes lining them. Mt. Kilimanjaro Great African Rift Valley
The formation of the Atlantic Ocean
Divergent Plate Boundaries In the Ocean Ridge Action: oceanic plates move apart Sea floor spreading Mid-Ocean Ridge Example: Mid Atlantic Ridge Longest mountain Range On Land Rift Action: Continental crust pull apart Examples: Iceland, Great Rift Valley in East Africa Oceans and Seas form Example: Atlantic Ocean and Red Sea Volcanoes Example: Mt. Kilimanjaro
Tree Map Divergent Plate Boundary Plate MovementOcean: Ridge Land: Rift Action: Sea-floor spreading Example: Mid Atlantic Ridge Oceans and Seas form: Examples: Atlantic Ocean and the Red Sea A place where to plates move apart, or diverge Action: Continental crust pull apart Examples: Iceland, Great Rift Valley in East Africa Oceans and Seas form Example: Atlantic Ocean and Red Sea Volcanoes Example: Mt. Kilimanjaro
Convergent Plate Boundaries 1.Ocean crust to ocean crust collision 2.Ocean crust to continental crust collision 3.Continental crust to continental crust collision The place where two plates come together, or converge. Three types of convergent plate boundaries:
Tree Map Name of plate boundary Draw arrows to indicate direction the plates move in relationship to each other. Create a Tree map of the 3 types of convergent boundaries, the events that occur there, and an example of each occurrence. i.e. action, formations, examples Compare the items in your map, which convergent boundary type does NOT result in volcanoes? Why?
Trench Island arc Aleutian Islands
Oceanic - continental convergence E.g. Andes mountains The forces of plate tectonics are responsible for the formation of the Andes. The Nazca plate and a part of the Antarctic plate have been subducting beneath the South American plate, which is a process that continues today and causes earthquakes andvolcanic eruptions in the regionplate tectonicssubductingearthquakesvolcanic eruptions
The sub-continent of India has collided with the Eurasian continent to form the Himalayas
Convergent Boundaries 3 types of convergent boundaries Ocean to ocean crust Crust melting forms volcanic island arc, ex Aleutian Islands Volcanoes – Philippines- Mt Pinatubo Subduction forms trench Ocean to continental crust Crust melting forms volcanic mountain ranges, ex Andes, cascade range, Mt Rainer, Mt Baker Subduction zones forms, trenches, Ocean crust denser than continental crust. Ocean crust slides/subducts under the continental crust Continental to continental crust No melting of crust = no volcanoes No subduction Folding of crust = Non-volcanic mountains are formed -Example Mt Everest
Tree Map Convergent Plate Boundaries Ocean to ocean crust Ocean to continental crust Continental to continental crust Crust melting forms volcanic island arc, ex Aleutian Islands Volcanoes – Philippines- Mt Pinatubo Subduction forms trenches Crust melting forms volcanic mountain ranges, ex Andes, cascade range, Mt Rainer, Mt Baker Subduction zones forms trenches Ocean crust denser than continental crust. Ocean crust slides/subducts under the continental crust No melting of crust = no volcanoes No subduction Folding of crust = Non-volcanic mountains are formed -Example Mt Everest
Transform Boundary A place where two plates slip past each other, moving in opposite directions
Pacific plate North American plate
San Andres Fault
Earthquake in action nt/visualizations/es1005/es1005page01.cfm?chapter_no= visualization nt/visualizations/es1005/es1005page01.cfm?chapter_no= visualization
Transform plate boundary Action: Earthquakes Forms: fault Example: San Andres fault No crustal melting = No volcanoes
Transform Boundary Draw arrows to indicate direction the plates move in relationship to each other. Name a location of a transform boundary. Name the event that occurs at transform boundaries. Could a volcano erupt in Los Angeles? Why or why?
Transform Boundary Direction Is a place where two plates slip past each other Forms Faults Earthquakes Example: San Andres fault No crustal melting = No volcanoes Crust is neither created nor destroyed