The Big Crack Up!

Explain the causes of earthquakes and volcanic eruptions. LEARNING TARGET 4: Describe plate movements that cause ocean basins, ocean trenches, and mountains to form; Explain the causes of earthquakes and volcanic eruptions.

EARTH: A GIGANTIC RECYCLING CENTER!

Plate Tectonics The theory of plate tectonics is based on the evaluation of scientific evidence and observation- The Scientific Method Continental Drift hypothesis Seafloor Spreading hypothesis

Convergent Divergent Transform Plate Boundaries Convergent Divergent Transform

Plate Tectonics Explains the configuration of topographic features of the Earth- mountains, valleys, volcanoes, islands, oceanic trenches, faults

Tectonic plates Are composed of the lithosphere Move as a coherent mass May contain oceanic crust and continental crust

Plate Boundaries Where does the energy come from to move plates? Where does it go? Topographic features on the Earth’s surface reflects what is happening in the mantle.

Convergent Plate Boundary Volcanic arc Oceanic crust subducts under continental crust Melting occurs at about 100 miles down Hot more buoyant material rises

Volcanic Arc Oceanic and continental crust Cascade Range, Andes, Alaska Characteristics: large volcanoes; subduction zone; trench; oceanic crust subducts under continental crust

Convergent Plate Boundary    Convergent Plate Boundary Map and cross-section views of the subduction zone The oceanic Juan de Fuca plate subducts under the continental North American Plate

Convergent Plate Boundary Two oceanic crusts Oceanic crust subducts under opposing oceanic crust Oldest oceanic crust subducts

Island Arc Japan, Indonesia, Philippines, Caribbean, Aleutian Islands

Convergent Plate Boundary Earthquakes trace the SUBDUCTING SLAB to about 500 miles or 650 kilometers Gold dots represent earthquake hypocenters

Sketch a cross-section of a convergent plate boundary that contains an oceanic crust. Label with the following terms: Subduction zone Trench Area of melting Area of volcanism Arrows indicating direction of plate movement

Convergent Plate Boundaries Two continental crusts Neither subduct due to buoyancy of crusts Mountains form

India collided with Asia about 40 million years ago Mt. Everest, 29,000 feet

Divergent Plate Boundary Two plates move apart Run through ocean basins

Divergent Plate Boundaries New crust forms at mid-oceanic ridges. The seafloor spreads out. This is Seafloor Spreading.

In most locations, mid-ocean ridges are 6,500 feet (1,980 m) or more below the surface of the oceans. In a few places, they reach above sea level and form islands. Iceland (North Atlantic), the Azores (west of Portugal), and Tristan de Cunha (south Atlantic between southern Africa and South America)

How Does Seafloor Spreading Affect Neighboring Plates?

East Africa Rift Zone Continental crust is beginning to pull-apart forming a rift valley

Process of Ocean Basin Formation

Sketch a cross section of a divergent plate boundary. Label with the following terms: rift valley; oceanic ridge; oceanic crust; location of melting and volcanism; and arrows indicating direction of plate movement .

Transform Plate Boundary

Transform Plate Boundary The tectonic plates pass by each other Connected to other plate boundaries San Andreas Fault Label the plates, their movement directions, and the San Andreas Fault

Hot Spots Animation of Formation Stationary plumes of hot material that initiate at the core/mantle interface Hawaii: the plume is beneath oceanic crust

Hot Spots

Hot Spots Yellowstone is associated with a hot spot under continental crust

Name the landform associated with oceanic crust subducting under continental crust. Oceanic crust?