Plate Tectonics

Plate Tectonics

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Plate- Separate sections of Earth's lithosphere

Pieces of the Earth's lithosphere are in constant, slow motion, driven by the convection currents in the mantle

Plate Boundaries

- Where the edges of different pieces of the lithosphere meet

- Faults which are breaks in Earth's crust where rocks have slipped past each other form along these boundaries

Three types of plate boundaries

- Transform

-Divergent

-Convergent

Multiple Choice

Which type of boundary involves the plates moving horizontally, side by side?

• convergent

• divergent

• transform

Divergent Boundary

- Place where 2 plates move apart

-Most occur in the ocean and form mid-ocean ridges

-When they occur on land, rift valleys form

Multiple Choice

When a divergent boundary occurs on land, which landform does it create?

• mid-ocean ridge

• rift valley

• new ocean floor

• subduction zone

Divergent Oceanic

-Example-Mid Atlantic Ridge

Divergent Continental

-Great Rift Valley in East Africa

Transform Boundary

-Place where two plates slip past each other side by side

- Crust is neither created nor destroyed

-Earthquakes frequently occur along these boundaries

Multiple Choice

What are transform boundaries known for?

• earthquakes

• volcanoes

• mid-ocean ridges

• rift vallies

Transform Boundary

-Boundary between the pacific plate and American plate in California

-The San Andreas Fault

Convergent Boundary

-Place where two plates come together

-There are 3 types

Oceanic crust and continental crust

Oceanic crust and oceanic crust

Continental crust and continental crust

Oceanic-Continental Convergent Boundary

-Oceanic crust is more dense than the continental crust so it sinks below the continental crust and is returned to the mantle

-This is called subduction

-Volcanoes and deep ocean trenches occur

Multiple Choice

The process when one crust goes under another is called

• sea floor spreading

• convergency

• subduction

• rifting

Continental- Oceanic Convergent Boundary

Ring of Fire

Oceanic-Oceanic Convergent Boundary

-When the two oceanic plates collide the older, more dense plate goes under the other oceanic plate and returns to the mantle

-volcanoes and deep ocean trenches occur

Multiple Choice

Which of the following does not occur at a continental-oceanic convergent boundary?

• volcano

• deep ocean trench

• mountain

Oceanic-Oceanic Convergent Boundary

-Forms Island Arcs (Strings of islands)

Multiple Choice

When 2 oceanic crusts collide, which one subducts?

• The older crust

• The newer crust

• can not tell from information given

Continental- Continental Convergent Boundary

-Neither plate is dense enough to sink into the mantle

-Plates crash head on and squeeze crust into mountain ranges

Continental-Continental Convergent Boundary

-Forms mountains

-Himalayas were formed this way

Multiple Choice

What is formed when a continental crust collides with another continental crust?

• volcanoes

• earthquakes

• deep ocean ridges

• mountains