5.1 Plate Tectonics

5.1 Plate Tectonics

I can explain the structures and processes involved with plate tectonics.

I can

• a) identify the mechanical layers of the Earth.

• b) explain convection in the mantle and how it relates to plate tectonics.

• c) evaluate the evidence for plate tectonics.

5.1.a

I can identify the mechanical layers of the Earth.

Compositional Layers Vs. Mechanical Layers

• The internal layers of Earth can be classified, or named two different ways.

• COMPOSITION - by what each layer is MADE OF

• MECHANICAL - by how each layer BEHAVES

Composition: Crust Types

• Continental: Very thick, less dense, made of granite, older than oceanic crust.

• Oceanic: Thinner, denser, made of basalt, younger than continental crust.

Mechanical Layers

• Lithosphere: This is SOLID and includes the crust and the solid upper part of the mantle

• Asthenosphere: This is a very thick LIQUID that is almost solid and flows like warm marshmallows. It is part of the mantle.

• Mesosphere: This is SOLID and like hot asphalt. It makes up the majority of the mantle

Mechanical Layers Continued

• Outer Core: This layer is hot, LIQUID metal.

• Inner Core: This layer is SOLID metal because the pressures are so high in the center of the Earth.

Multiple Choice

Which crust type is thicker and less dense.

• Continental crust

• Oceanic Crust

Multiple Choice

What layer is a semisolid and acts like a plastic?

• Lithosphere

• Asthenosphere

• Mantle

• Crust

Multiple Choice

Which layer of Earth is made up of tectonic plates?

• Asthenosphere

• Lithosphere

• Outer Core

• Inner Core

Multiple Choice

Which of the following describes the outer core?

• Liquid

• Plastic

• Solid

• Gas

Multiple Choice

Part of the mantle that is partially molten tock/semi-solid/melted marshmallows

• Lithosphere

• Asthenosphere

• Inner core

• Outer core

5.1.b

I can explain convection in the mantle and how it relates to plate tectonics.

Convection Currents: What are they?

• CONVECTION is the transfer of heat by moving substances - hot things rise and cool things sink.

  When parts of the mantle heat, it rises and pushes the lithosphere apart, and solidifies to make new crust.

Convection Currents: What are they? Continued

• The CONVECTION CURRENTS help to push and pull the lithospheric plate towards the trenches, where they sink and melt back into the mantle.

Multiple Choice

Where do convection currents occur in the Earth?

• Lithosphere

• Asthenosphere

• Outer Core

• Inner Core

Multiple Choice

Where the convection currents rise, what is occurring on the surface?

• Plates are converging

• Plates are subducting

• Plates are diverging

Multiple Choice

What process causes the plates to move?

• Convection

• Conduction

• Radiation

5.1.c

I can evaluate the evidence for plate tectonics.

Continental Drift Theory

• Alfred Wegener (1912)

• Pieces of Evidence:

• Continents having puzzle like fit

• Fossils: Matching fossils across oceans

• Mountains: Matching mountains across oceans

• Originally not accepted. Could not explain the WHY

Seafloor Spreading Theory

• Harry Hess & Robert Dietz (1960)

• This theory states that new oceanic crust is made at mid-ocean ridges, and destroyed at trenches.

Seafloor Spreading Evidence

• Seafloor age: Oceanic crust is younger at mid ocean ridges, and older near subduction zones.

• Magnetic reversals: Pole reversals are documented in the rocks

Plate Tectonic Theory

• John Tuzo Wilson (1965)

• States that the Earth's Lithosphere is broken into plates that are in constant motion relative to each other due to convection currents in the asthenosphere

• Combined Continental drift theory and Sea Floor Spreading theory

Continental Drift + Seafloor Spreading= Plate Tectonic Theory

Multiple Select

Which pieces of evidence supports the continental drift theory? (Check all that apply)

• Seafloor age

• Continent puzzle piece

• Matching fossils

• Magnetic reversals

• Same mountains on different continents

Multiple Select

Which pieces of evidence supports the seafloor spreading theory? (Check all that apply)

• Seafloor age

• Continent puzzle piece

• Matching fossils

• Magnetic reversals

• Same mountains on different continents

Multiple Choice

Why was Alfred Wegener's theory not initially accepted by scientists?

• He had no evidence

• He couldn't explain why is was happening

• He couldn't explain what had happened

Multiple Choice

True or False: Plate tectonic theory is a combination of continental drift theory and seafloor spreading

• True

• False

Multiple Choice

What is the most recent supercontinent named:

• Gondwanaland

• Pangaea

• Laurasia

• Rodinia