Types of Plate Boundaries Divergent Plate Boundaries Convergent Plate Boundaries Transform Faults

Divergent Plate Boundaries   Mid-ocean ridges form along divergent boundaries. Magma pushes continental crust up causing it to break apart. Plates begin to move apart in opposite directions causing crustal material to slump downward, creating a rift valley. See animation.. Click here!!

Divergent Plate Boundaries   A linear sea is formed as water fills in the valley. Through continued divergence, an ocean basin forms, creating an ocean. Ex: Red Sea See animation.. Click here!!

Red Sea

Divergent Plate Boundaries   Mid-ocean ridges have oceanic rises and oceanic ridges. –Oceanic rises  gently sloping due to a fast rate of spreading. Ex: East Pacific Rise

East Pacific Rise

Divergent Plate Boundaries   –Oceanic ridges  have steeper slopes due to a slower rate of spreading. Ex: Mid-Atlantic Ridge

Iceland and Mid-ocean Ridge

Convergent Plate Boundaries   Plates are pushed together Oceanic crust is subducted and absorbed into the mantle creating a subduction zone Produces a deep- ocean trench and volcanic arc.

Three types of Convergence Oceanic/ Continental (Fig 1) Creates a subduction zone Subduction creates a deep trench On the continental plate, a continental arc forms parallel to the trench. Ex: Cascade & Andes Mountains

The Andes

Cascade Mountains

Three types of convergence Oceanic/ Oceanic (Fig 2) –Subduction creates a deep trench. –As one oceanic plate subducts, a chain of volcanic mountains form, producing an island arc. Ex: Aleutian Islands & Mariana Trench

Aleutian Island Arc

Marianas Trench

Three types of convergence Continental/ Continental (Fig 3) –As two continental plates collide, they buckle, fold and push upward to produce a mountain range. Ex: Himalayas

Transform Faults/Boundaries Plates slide past one another along faults in the lithospheric plate Crustal material is neither created nor destroyed Ex: San Andreas Fault

San Andreas Fault

Hot Spots & Mantle Plumes Hot spots are areas of continued volcanic activity NOT associated with plate boundaries. Ex: Hawaiian Islands & Yellowstone National Park Hot spots are fueled by regions of rising molten rock called mantle plumes. (pg 62) Super volcano?????Super volcano Old Faithful

Convection Cells and Magma Plumes

Seamounts & Tablemounts Underwater volcanoes are called seamounts. As seamounts break the surface of the ocean, they may become islands. Over time, the seamount’s peak erodes away as the seamount subsides, eventually becoming a flat-top tablemount or Guyot.

Hawaiian-Emperor Seamount

Coral Reef Formation Fringing Reef: grow close to land, associated with active volcanic islands. Ex: Kurumba Island in the Maldives

Coral Reef Formation Barrier Reef: Linear or circular reefs separated from land by a lagoon of water. Ex: Great Barrier Reef

Coral Reef Formation Atoll: By this stage, the volcano is completely submerged. All that remains is the reef and a lagoon. Ex: Atafu in S. Pacific Click Me

The Big Picture

1-Asthenosphere 2-Lithosphere 3-Hot spot 4-Oceanic crust 5-Subducting plate 6-Continental crust 7-Continental rift zone (young plate boundary) 8-Convergent boundary plate 9-Divergent boundary plate 10-Transform plate boundary 11-Shield volcano 12-Oceanic spreading ridge 13-Convergent plate boundary 14-Strato volcano 15-Island arc 16-Plate 17-Asthenosphere 18-Trench

And finally...