UNIT 2 STANDARDS: STATE OBJECTIVES: 2.1.1, LESSON 2 Plates Tectonics

Objectives By the end of the lesson you will have an introduction to Plate Tectonics including:  Vocabulary Terms and Relationships  Early Tectonic Theory  An overview of the different plates comprising the crust  What happens when plates collide  How new crust is formed  What drives the plate tectonics  Human interaction

Vocabulary Terms Rock CycleThe constant creation and destruction of the earth’s crust generated by the heat energy in the earth’s core. Tectonic PlateThe large section of the earth’s crust that moves as one “piece” across the mantle. PangeaSupercontinent FaultAn area where two plates “slip” past each other generally producing earthquakes at the zones. EarthquakeResulting from slipping plates, normal process that changes the surface of the earth.

Vocabulary Terms Sea-Floor SpreadingMid-Atlantic Ridge where new crust is made. Subduction ZoneAreas where the old crust is pulled back into the mantle.

Earth Crust: A Collection of Plates

Plate Tectonic Theory Recall the comparison of the earth to an egg. The shell of the egg is the hard outer layer. The hard outer layer of the earth is called the crust. Has the earth’s landmasses always looked the same as they do now? The movement of the continents was discovered and explained in 1912 by a German scientist named Alfred Wegener. He called the idea continental drift. Wegener had studied the shapes of the continents and found that they looked like they used to fit together. If you look closely, you can still see how the continents used to fit together to form one large land mass. We called that old continent Pangaea.

Pangea: Super Continent Below is a representation of Pangea Look to see if you recognize today’s continents.

Plate Movement The continents are being pushed apart by the movement of magma in the mantle. The Rock Cycle drives plate tectonics. Each plate pushes against the next plate in one of three ways:  Sometimes the plates pass each other sideways.  Sometimes the plates are pulled away from each other.  Sometimes one plate rides up and over another plate. Plate Boundaries are where the tectonic plates touch. Fault zones occur in these boundaries.

Sideways Plate movement Some plates rub against each other as they pass. This causes pressure to build up between the plates, and they “slip” after hundreds of years to release the pressure. We call these places where the plates pass each other sideways faults. When the ground “slips” at the fault lines, we have earthquakes. When pressure has been building up for hundreds or thousands of years, earthquakes can be very strong. Earthquakes can occur on land or under the sea, wherever plates pass sideways against each other.

Shake Rattle and Roll What areas of the earth are prone to earthquakes? What earthquakes have you heard of in history?history Where are earthquakes likely to occur in the US?US What can people to to prevent earthquakes? What can people do to minimize the damage from earthquakes?

Plates Pulled Apart: Sea-Floor Spreading The plates can be pulled away from each other. We call this plate movement sea-floor spreading. This is happening now in the middle of the Atlantic Ocean. The formation of the Mid-Atlantic Ridge is where new crust is made. New land is created as hot, melted rock from the earth’s mantle rises to fill the gap between the plates. The magma cools and becomes hard rock. LINK:

Picture time Discussion Discuss what is happening

New Crust: Bubbling Up Remember the magma in the mantle is hot, molten rock. It is under pressure and will be forced up through the cracks in the earth. Mid-Atlantic Ridge is the location where the sea- floor is spreading apart. This spreading allows for the magma to “surface” and build new crust. Sea-Floor Spreading Animation

Mid Atlantic Ridge

Subduction: Plates on top of Plates Sometimes one plate moves under another plate. The lower plate is pushed down beneath the surface of the earth and melted by the heat of the mantle. The upper plate is pushed up. Since the plates or continents are made of rock below the soil, it is the rock that is pushed up. The displaced rock is what forms mountains. Mountains are still being formed in such places as California and northern India. There are also mountains rising in the middle of the sea where plates come together underwater. LINK:

Subduction Zone

Subduction Zone: West Coast

Volcanoes: On the Edge Volcanoes are common on the edges of plates as continents move and shift. Volcanoes are common on the edges of plates as continents move and shift This is because the weakest spots in the earth’s crust are along these lines. Hot, melted rock from inside the earth forces its way upward to the earth’s surface. Earthquakes are also most common in these places, where the movement of the plates causes pressure to build up. LINK:Nat Geo 3:08 MinutesNat Geo 3:08 Minutes EruptionsEruptions2:31

Human Interactions Discuss the interactions of humans with the earth’s crust and the movement of the crust.  Human Populations  Clusters of humans near water  Plate Boundaries and Human Interactions  Danger to Populations  Earthquakes  Volcanoes  Tsunamis

Summary of Plate Movements

Video Quiz Describe what is happening in each. 1. Clip 1 Clip 1 2. What is moving ? What is moving ? 3. What is coming Out? What is coming Out? 4. What is #3 called once it is on the surface? What is #3 called once it is on the surface?

Continental drift edded&v=uGcDed4xVD4 edded&v=uGcDed4xVD4 Layers of the earth 2:45 (Rap) Layers of the earth Good Review Tectonics14:05 Good Review Tectonics

Plate Tectonic Review Overall Plate Tectonic Review

Resource volcanoes.html