Volcanoes and Plate Tectonics

Plate Tectonics & Volcanoes

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Pangea & Plate Tectonics

• All of the continents formed one major landmass called Pangaea.

• Scientists have determined this using the fossils found on different continents of the same species, mountain formations, and similar climate signs.

Sea Floor Spreading

• Cracks along the ocean floor allow magma to come up and cool.

• The cooling magma forms a new crust.

• The old crust breaks and the two parts move away from one another.

• Oceanic crust is newer than continental crust.

Why is the Earth the same size?

• New crust is being formed every day at mid-ocean ridges.

• However, the old crust is dense and heavy so it sinks in subduction zones or trenches (deepest parts of the oceans).

• The old crust is melted back into magma and the process begins again.

Multiple Choice

Oceans plates sink back into the mantle at _______________ zones, keeping the crust the same size.

• Mid-ocean ridges

• Subduction (trenches

• Transforming

Multiple Choice

_____________________ are undersea that are the deepest part of the ocean.

• Divergent trenches

• Ocean trenches

• Transform trenches

• Mid-ocean trenches

Multiple Choice

______________________ continually adds materials to the ocean floor creating ocean floor.

• Sea-floor spreading

• Ocean trenches

• Divergent mid-ocean ridges

• Convergent mid-ocean ridges

Multiple Choice

What evidence supports that the continents were one giant land mass?

• Rock formation, weather, fossils

• Mountain formation, fossils, climate

• Land features, fossils, climate

• Valleys, Ocean trenches, climate

Plate Tectonic Theory

• Earth's lithosphere (crust and upper mantle) is moving around on plates.

• The plates move in different directions and at different speeds.

• Some plates have whole continents, and some have only oceanic crust.

Plate Boundaries: Convergent

• Convergent boundaries form where two plates COLLIDE or HIT.

• 3 things can happen at a convergent boundary.

• 1. Continent-Continent: the plates buckle and thicken forming mountains.

• 2. Continent-Oceanic: the oceanic crust subducts (sinks) because it is denser (heavier), volcanic mountains can be found here.

• 3. Oceanic-Oceanic: the oceanic crust that is denser (heavier) will subducts (sinks), volcanic islands can be found here.

Multiple Choice

The edges of plates are called....

• convection

• boundaries

• subduction

Multiple Choice

When one plate forces it's way under another plate.

• convection

• boundary

• subduction

Multiple Choice

What geological feature would an oceanic-continental convergent boundary create?

• volcanic mountains

• mountains

• volcanic islands

Multiple Choice

What geological feature would an continental-continental convergent boundary create?

• volcanic mountains

• mountains

• volcanic islands

Multiple Choice

What geological feature would an oceanic-oceanic convergent boundary create?

• volcanic mountains

• mountains

• volcanic islands

Plate Boundaries: Divergent

• Divergent Boundaries move away from one another.

• Think of DIVIDE or SPLIT

• This is common along mid-ocean ridges where the crust is thinner allowing for magma to rise.

• On land, this occurs in rift valleys, when two continents move away from one another.

• 
  

Plate Boundaries: Transform

• When two plates move past each other horizontally, it is a transform boundary.

• The plates don't slide smoothly and scrape on one another.

• This is the common cause of earthquakes.

Multiple Choice

Name the boundary

• convergent boundary

• divergent boundary

• transform boundary

• sergent boundary

Multiple Choice

What kind of plate boundary is shown here?

• divergent

• convergent

• transform

Multiple Choice

A subduction zone is formed...

• when one tectonic plate sinks below another

• at every type of convergent plate boundary

• at every type of divergent plate boundary

• at transform boundaries

Multiple Choice

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

• Volcano

• Mountain

• Rift

• Island Arc

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.

Multiple Choice

What kind of plate boundary is shown here?

• divergent

• convergent

• transform

Multiple Choice

What kind of plate boundary is shown here?

• divergent

• convergent

• transform

• subducting

What are Volcanoes?

• A volcano is any place where gas, ash, or melted rocks come out of the ground.

• They can be found everywhere on Earth- in the ocean or on land.

• Magma is less dense so it rises to the surface and escapes through vents or openings.

• Magma on land is called lava.