plate tectonics objective(s): swbat describe the layers of the earth. swbat describe the plate...
TRANSCRIPT
Plate TectonicsObjective(s): SWBAT describe the layers of the Earth.
SWBAT describe the plate tectonics theory including, how plate tectonics operating over geologic time has changed the patterns of land, sea, and mountains on Earth’s surface.
SWBAT differentiate between the features of the three different kinds of plate boundaries.
HA HA HA
Structure of the Earth
http://www.youtube.com/watch?v=Q9j1xGaxYzY
Structure of the Earth
GPS (Global Positioning System) – 24 satellites orbiting the Earth at a height of 20,200 km.
Divergent Plate Boundary: Sea Floor Spreading
When two plates move away from each other.
Divergent Plate Boundaries:Sea Floor Spreading
Divergent Plate Boundaries Most found on the seafloor where they form
mid-ocean ridges. (two plates moving away from one another)
New crust forms at mid-ocean ridges, thus younger rock is closer to the spreading center.
Sea-floor spreading: mantle asthenosphere (top part of mantle) slowly rises upward as magma (molten rock). Magma rising up is less dense than the surrounding rock and forms volcanoes in the central valley of the mid-ocean ridge.
Divergent Plate Boundary:Mid-Atlantic Ridge
Divergent Plate Boundary:Mid-Atlantic Ridge - Iceland
Divergent Plate Boundary: Rift Valley
Divergent Plate Boundaries: Rift Valley
Rift Valley: a large, long valley on a continent, formed where the continent is pulled apart by forces produced when mantle material rises up beneath the continent.
They can occur in both continental and oceanic plates.
Divergent Plate Boundary:East African Rift Valley
Convergent Plate BoundaryTwo lithospheric plates move toward each other.
Convergent Plate BoundaryWhen Continental plates move toward each other.
A look at the big picture
A Map of the Major Plates of the World
A World View of Boundary Types
Key: 1. Divergent plate boundaries 2. Transform plate boundaries 3. Convergent plate boundaries 4. Plate boundary zones 5. Selected prominent hotspots
A Closer Look at the West Coast
Convergent Plate Boundaries
(two plates moving toward one another)
3 types of convergent plate boundaries Subduction – the movement of one plate downward
into the mantle beneath the edge of the other plate at a convergent plate boundary. The downgoing plate is always oceanic lithosphere. The plate that stays at the surface may be either ocean lithosphere or continental lithosphere.
*Old crust is recycled at subduction zones
Convergent Plate Boundaries1. Oceanic-Oceanic: One plate has become denser
than the other as a result of cooling. The process of subduction creates a deep-sea trench. As one plate goes down into the mantle asthenospehere, magama is produced at a certain depth. The magma rises up to the ocean floor to form a chain of volcanic islands (volcanic island arc)
Convergent Plate Boundary
Oceanic-Oceanic Convergent Boundary
Convergent Plate Boundaries2. Oceanic-Continental: The oceanic plate subducts
beneath the continental plate. This forms a trench and a volcanic arc along the edge of the continental plate. (mountain ranges composed of many volcanoes)
Convergent Plate Boundary
Oceanic-Continental-
Example: Andes Mountains
Convergent Plate Boundaries3. Continental-Continental: The colliding edges of the
continents are crumpled and uplifted to form a mountain range.
Suture Zone: the zone on the Earth’s surface where two continents have collided and have been
welded together to form a single continent.
Convergent Plate Boundaries: Continental-Continental: Himalyans
Transform Plate Boundaries
Two plates slide parallel to each other
Transform Plate Boundaries (plates slide horizontally past one another) Crust is deformed or fractured, not formed or
recycled
Characterized by long faults and shallow earthquakes
Many transform boundaries off-set mid-ocean ridges
Transform boundaries on continents is rare
Example: San Andreas Fault (several hundred kilometers long)
Transform Boundary on Land