The Theory of Tectonic Plates Chapter 7 Section
- Slides: 15
The Theory of Tectonic Plates Chapter 7 Section 3
The Theory of Plate Tectonics • The Earth’s lithosphere (crust and upper mantle) is divided into tectonic plates. • These plates move on top of the asthenosphere (lower mantle). • We know that these plates move in different ways.
Tectonic Plates
Tectonic Plate Boundaries • A boundary is a place where tectonic plates touch. • There are 3 types of tectonic plate boundaries: • Convergent • Divergent • Transform
The numbers on the map represent the rate at which plates are moving in centimeters.
Plate Movement
Convergent Boundary • When two plates collide, or move toward each other, the boundary is called convergent • There are 3 types of convergent boundaries, depending on what type of crust comes together. • Continental-continental • Continental-oceanic • Oceanic-oceanic
Convergent Boundary Continental-Continental • • • The two continental plates come together Buckle Thicken Push continental crust upward
Convergent Boundary Continental-Oceanic • Dense oceanic crust sinks below the continental crust and sinks into the asthenosphere. • This is a subduction zone. • Sub means below (submarine, subway) • Old ocean crust is pushed below the asthenosphere and gets remelted and recycled.
Convergent Boundary Oceanic-Oceanic • One oceanic plate sinks below the other. • Another subduction zone
Divergent Boundary • Two tectonic plates move away from each other. • On the sea floor at the mid ocean ridge this is called sea floor spreading. • As the plates move apart, magma rises to fill the gaps. • The magma is cooled and forms new ocean floor. The volcanic country of Iceland, which straddles the Mid-Atlantic Ridge, offers scientists a natural laboratory for studying on land the processes also occurring along the submerged parts of a spreading ridge. Iceland is splitting along the spreading center between the North American and Eurasian Plates, as North America moves westward relative to Eurasia.
Divergent Boundary On-land exposure of the Mid-Atlantic Ridge in Iceland. Sea Floor Spreading
Transform Boundary • Two tectonic plates move past one another. • Their edges are jagged and irregular. • As they grind together and jerk, they slide past each other creating earthquakes.
Possible Causes of Plate Movement • Convection Currents: hot rock deep in the Earth rises, cooler rock sinks. This movement of magma causes plates to move • Ridge push • Slab pull
Tracking Tectonic Plate Movement • Plates move very slowly, centimeters to inches a year. • GPS, Global Positioning System, measures the rate of movement. • Radio signals beam continuously from satellites to the Earth. • By recording the time it takes for the Ground station to move a given distance, scientists can measure the speed at which plates move. • Plate Boundary Animation • http: //www. classzone. com/books/earth_science/terc/content/visualiz ations/es 0804 page 01. cfm? chapter_no=visualization • http: //www. wwnorton. com/college/geo/ege o/animations/ch 2. htm
- My plates pyramid tectonic plates
- Ring of fire hotspots
- Grand banks earthquake of 1929
- What causes the plates to move
- Convergent boundary oreo
- Mount fuji tectonic plates
- What is the border between two tectonic plates called
- Tectonic plates with names
- Example of an investigative question
- Plate tectonics apes
- Shield volcano
- Tectonic plates
- Tectonic plates interact at places called plate
- Struture of the earth
- Tectonic plates move
- Divergent