Plate Boundaries

Theory of Plate Tectonics/ Plate Boundary Interactions

The lithosphere is broken into Tectonic Plates

• The lithosphere is made from the crust and the uppermost part of the mantle

• The lithosphere is rigid, brittle rock

• These plates float on the asthenosphere

How do the plates MOVE?

• Convection currents in the asthenosphere drive the movement of lithospheric plates

Multiple Choice

Tectonic plates consist of

• continental crust

• mesospheric crust

• both continental and oceanic crust

• oceanic crust

Divergent Plate Boundary

• Where two plates move away from each other. (divergent = divide)

  
  

Divergent

• When oceanic plates diverge (sea-floor spreading), magma oozes out of the divergence, forming a mid-ocean ridge (underwater mountains)

  • Mid Atlantic Ridge

Oceanic-Oceanic

• When continental plates diverge, it forms a rift valley

  • East African Rift Valley

Continental-Continental

Divergent

Oceanic-Oceanic

Continental-Continental

Convergent Plate Boundary

Two plates move toward each other. (convergent= collide)

Subduction: occurs when more dense tectonic plate slides under the less dense tectonic plate

Convergent

• Oceanic Plate always subducts under continental plate

• forms volcanoes & trenches (can also have some earthquakes)

Oceanic-Continental

• Forms mountains

  • Himalayan Mountains

Continental-Continental

Convergent

Oceanic-Continental

Continental-Continental

Convergent

• Denser, older plate subducts

  • Forms deep sea trenches & Island Arc Volcanoes

    • Hawaiian Islands

Oceanic-Oceanic

Transform Plate Boundary

• Two plates slide past each other

  • Causes Earthquakes

  • San Andreas Fault

Transform Plate Boundary

Draw

Draw lines where you think the plate boundaries are on the map.

Multiple Choice

What two crustal features occur near every subduction zone?

• Volcanoes and Trenches

• Rift Valleys and Mid Ocean Ridges

• Volcanoes and Rift Valleys

• Mid Ocean Ridges and Trenches

Multiple Choice

What geologic feature/event would you most likely to find at a divergent boundary between two pieces of continental crust?

• Mid-Ocean Ridge
• Mountain
• Rift Valley
• Island Arc

Match

Match the plate boundary to its diagram.

Divergent

Convergent

Transform

• Divergent

• Convergent

• Transform

Multiple Choice

What geologic feature/event would you most likely to find at a divergent boundary between two pieces of oceanic crust?

• Rift Valley
• Mid-Ocean Ridge
• Island Arc
• Flat land

Multiple Choice

What geologic feature/event you be most likely to find at a transform boundary?

• Earthquakes
• Volcanoes
• Mountains
• Rift Valleys

Multiple Choice

The diagram shows a landform on Earth. How did the movement of Earth’s plates form the landform?

• Two oceanic plates slid past each other.

• Two continental plates collided.

• One continental plate slid past an oceanic plate.

• One continental plate subducted beneath an oceanic plate.

Multiple Choice

Use the diagram to answer the question. What results as the two oceanic plates converge?

• formation of a deep sea trench and island volcanoes

• earthquake activity and appearance of a transform fault

• volcanic eruption along both oceanic plate edges

• formation of a continental mountain range

Multiple Choice

What are the two types of crust

• continental and oceanic
• ocean and upper
• lower and upper
• pizza and subway

Multiple Choice

A mid-ocean RIDGE is located at the boundary of two tectonic plates. Which diagram correctly models the relative plate motion on each side of a mid ocean ridge?

Match

Match the plate boundary to its definition.

• Plates spread apart

• Plates come together

• Plates rub against each other

Divergent

Convergent

Transform

• Divergent

• Convergent

• Transform

Multiple Choice

In the Atlantic ocean, where is the youngest seafloor located?

• Towards the edges

• Youngest seafloor is in the middle of the ocean

Multiple Choice

Which plate is the SUBDUCTING or sinking plate in a convergent oceanic-continental boundary?

• The dense oceanic plate

• The Thick continental plate

• Neither

• Both ocean and continental plate can sink.

Multiple Choice

What event occurs at the letter A?

• earthquake
• subduction
• volcanism