Plate Tectonics and Plate Boundaries Lessons

Plate Tectonics and Plate Boundaries

Year 10 EES

​What we will cover:

• continental drift --> plate tectonics

• convection currents

• divergent, convergent, and transform plate boundaries

• drawing plate boundaries

• intro on earthquakes

Multiple Choice

Which of these phenomenon is not directly caused by plate tectonics

• Volcanic eruptions

• Earthquakes

• Tsunamis

• Landslides

Open Ended

What are the types of plate boundaries?

Multiple Choice

A Plate Boundary where two plates move toward each other is called

• Convergent Boundary
• Divergent Boundary
• Transform Boundary
• Subduction

Multiple Choice

A plate boundary where two plates move away from each other is called

• Divergent Boundary
• Convergent Boundary
• Transform Boundary
• Subduction

Multiple Choice

Boundary between two plates that are sliding past each other

• transform

• divergent

• convergent

• strike-slip

Multiple Choice

The scientist who developed the big idea called "sea-floor spreading"

• Alfred Wedgener

• Harry Hess

• Edward Dutton

• Ortelius

Multiple Choice

The idea that the continents were once part of a single landmass that broke apart and

moved is

• Continental Drift

• Tectonic Plates

• Transform

Multiple Choice

Why did no one believe Wegener's thoery that the continents were once together?

• He could not explain HOW the continents moved

• He didn't have evidence

• His data was wrong

• He didn't use the right technology to gather data

Multiple Choice

The movement of the tectonic plates is caused by______.

• convection currents

• rotation of the Earth

• movement of materials in the outer core

• revolution of the Earth

​The shift from continental drift to plate tectonics

• Continental drift provided a theory for how the continents used to fit together, and must have moved over time

  • Evidence: matching coastlines, fossils found on now separate continents, matching geological evidence, glacial striations

• However, he could not propose HOW this actually happened

• Plate tectonics was able to do this

• Plate tectonics:

• The crust and upper mantle make up the lithosphere

• The lithosphere is broken into 10 major and many minor plates

• These plates float on a layer of magma in the asthenosphere

• The magma moves due to convection currents

• The plates move only a few centimetres a year

• There is either continental or oceanic crust that makes up the plates

​Types of crust:

• Oceanic crust

  • thinner (6km)

  • denser - due to chemical make up

  • younger

  • formed by diverging plates

  • under the oceans

• Continental crust

  • thicker (30-70km)

  • less dense

  • older

  • formed by converging plates

  • makes up the continents

Multiple Choice

Which is more dense?

• Continental Crust

• Oceanic Crust

Multiple Choice

The fact that similar fossils are found on both sides of the ocean is evidence of____.

• magnetic reversal

• continental drift

• seafloor spreading

• oceanic drift

​Convection currents

• Plates float on magma in the asthenosphere

  • More of a solid than a liquid layer due to the pressure it's under

  • But it is constantly moving

• As the magma heats up it becomes less dense and spreads out, once it hits the tectonic plate on top it cools, becomes more dense and sinks

​Plate Boundaries

• Tectonic plates meet at boundaries

• Convergent, divergent, and transform boundaries exist

• You will need to know the details of these plate boundaries, where they occur on Earth, and what tectonic processes they form

​Divergent boundaries

• If plates are moving away from each other

• When plates move apart, magma from the mantle comes to the Earth's surface

• As the magma cools, new oceanic crust is formed

• Often form Mid Ocean Ridges (MORs)

  • E.g. Mid Atlantic Ridge

• Rock further from the MOR is older

• Tectonic processes = earthquakes, convection, magma rising

• Examples:

​Convergent boundaries:

• Plates that collide with each other

• There are 2 types (dependent on the composition of the plates):

  • Oceanic-Continental

    • Causes subduction, as the oceanic crust (more dense) sinks under the continental crust

    • Deep ocean trenches form

    • Earthquakes and volcanic activity - due to heat and friction released

    • E.g. Andes mountain ranges

    • Oceanic-oceanic also does the same --> the older/colder plate will subduct beneath the other

  • Continental-Continental

    • Nothing subducts, so they go up

    • Forms mountain ranges and earthquake activity

    • E.g. Himalayas

​Transform boundaries

• Two plates slide against each other in opposite directions

• Pressure builds up and can release in the form of earthquakes

• E.g. San Andreas fault in California

​Earthquakes:

• When pressure builds up due to plate movement, suddenly, the pressure can become too much and the plates will 'jump' to a new position

• This jump causes rocks to break and energy to be released - some of this energy is released in the form of seismic waves

  • Seismic waves cause earthquakes

• Most earthquakes will occur at plate boundaries or on fault lines

Multiple Choice

What kind of boundary is shown in this image?

• Divergent

• Convergent: Subduction

• Convergent: Collision

• Transform

Multiple Choice

The San Andréas fault in California is one example of a...

• Divergent boundary

• Convergent boundary

• Transform boundary

• All of the above

Multiple Choice

The Himalayan mountains have some of the highest peaks like Mt. Everest, on which type of convergent boundary are they located?

• Oceanic/Continental
• Oceanic/Oceanic
• Continental/Continental
• None of the above

Multiple Choice

This image represents this type of boundary

• Divergent
• Transform
• Convergent
• Subduction

Multiple Choice

Where are earthquakes MOST LIKELY to occur?

• close to the equator

• close to the center of tectonic plates

• at divergent or convergent plate boundaries

• at transform plate boundaries

Multiple Choice

The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.

• stressing

• seafloor spreading

• subduction

• shearing

Multiple Select

What is happening in this image? Select all correct answers.

• Oceanic-Continental convergent boundary

• The more buoyant plate is subducting under the other

• Pressure build up causes volcanic eruptions

• The denser plate subducts under the other

Multiple Choice

The image shows the Mid Atlantic Ridge. Which type of boundary occurs at this ridge where the ocean floor is spreading apart?

• convergent

• divergent

• transform fault

• reverse fault

Multiple Choice

The belt of volcanoes around the rim of the Pacific Ocean is called:

• Island arc
• Ring of Fire
• Lava plateau
• Hawaii

Multiple Choice

Thinner, more dense, younger crust, primarily basaltic, making ocean floor

• mantle

• continental crust

• oceanic crust

• asthenosphere

Multiple Choice

The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick

• mantle

• continental crust

• oceanic crust

• asthenosphere

Multiple Choice

The process that creates new seafloor as plates move away from each other at the mid-ocean ridges

• stressing

• seafloor spreading

• subduction

• shearing

​Up next?

• Earthquakes

• Tsunamis

• Volcanoes