Plate Tectonics Review

Continental Drift and

Plate Tectonics

Continental Drift Theory

•Proposed in 1912 by Alfred Wegener

•Hypothesis: Earth's continents were
once one large landmass (Pangaea)
but have moved over time

•Key ideas:
•Continents fit together like puzzle
pieces

•Large supercontinent breaking
apart

•Continents in motion

•The theory didn’t explain how the
continents have moved.

Evidence for Continental Drift

•Continents fit together like puzzle
pieces

•Similar fossils can be found on
different continents

•Index fossils: organisms that lived
during only one short period

•Fossil evidence on matching
edges of continents

•Law of Superposition: Each rock
layer is older than the one
above it

Multiple Choice

Which of the following evidences does NOT support the idea of Pangaea?

• A similarity in outline of the coastlines of eastern South America and West Africa

• Similar glacial deposits in Antarctica, Africa, South America, India and Australia

• Similar fossils found on separate continents far apart

• Salt concentrations in the oceans surrounding the continents.

Plate Tectonics Theory

•Proposed in 1960 by Harry Hess

•Scientific theory explaining how
major landforms are created

•Key points:

•Explains how convection
currents in Earth’s mantle
cause continents to move

•Explains the relationships
between fossils found in
different parts of the world.

Evidence for Plate Tectonics

•Seismic activity zones and plate boundaries

•Ring of Fire: area in the Pacific Ocean with
frequent earthquakes and volcanic eruptions

•Location of mountain ranges

•Magnetic striping in ocean floor rocks

•Correlation of fossil data from ocean drilling

Law of Superposition

•States in undisturbedrock layers, the oldest layer is at the

bottom

•Each layer is younger than the one below it

•These layers scientists determine relative ages of rock layers
and fossils

Oldest ->

Youngest ->

Other Evidence of Earth's Changes

•Rock formations and structures

•Glacial deposits and features

•Sea level changes

•Climate change evidence in ice cores and
sediments

•Radiometric dating of rocks and minerals

•Geomagnetic reversals recorded in rocks

Dropdown

The Law of Superposition states that ​

Select answer

rock is closer to the surface.

Multiple Choice

Which type of fossil is found in the most recently formed sedimentary rock layer?

• early horses

• dinosaurs

• armored fish

• trilobites

Multiple Choice

Layer 3 contains many fish and small mollusk fossils. Layer 3 most likely formed in which of these environments?

• Desert

• Ocean

• Forest

• Tundra

Multiple Select

What are TWO major forms of evidence did Wegener use to support his theory? 

• Similar rock and fossil evidence have been found on the coastlines of two or more continents.

• Glacier deposits have been found on two or more continents near the equator.

• Convection currents in the mantle move the Earth's crustal plates, causing plate boundaries to collide, separate, or slide against one another. 

What are the layers of Earth?

1.

Lithosphere (crust)

2.

Mantle (includes the
asthenosphere)

3.

Outer Core

4.

Inner Core

How do the Tectonic Plates move?

Convection currents occur within the asthenosphere this
movement causes the plates slowly and constantly in the
mantle.

Multiple Choice

What type of thermal energy transfer is responsible for the movement of Earth's tectonic plates?

• Conduction

• Convection

• Radiation

What are plate boundaries?

Earth’s plates meet and interact at areas
called boundaries.

3 Types
● Convergent
● Divergent
● Transform

What is a Convergent Boundary?

• An area of crust where 2 plates come together

• As the crust is destroyed, volcanoes and mountains can form.

• Subduction: when 1 plate goes underneath another (this can create a trench)

• Islands form slowly as the oceanic plate moves over a hotspot in the mantle.

Multiple Choice

The diagram above represents a chain of volcanic islands that are formed in a similar way as the Hawaiian Islands. What forms an island chain such as this?

• The islands form as the oceanic plate moves too quickly away from another ocean plate.

• The islands form from the movement of the oceanic plate underneath a land plate.

• The islands form slowly as the oceanic plate moves over a hotspot in the mantle.

• The islands form as a hotspot in the mantle moves underneath the oceanic plate.

What is Divergent Boundary?

• Area of crust where 2 plates are moving apart and create new

land

• Can be found on landand in oceans, but most occur at the

mid-ocean ridge.

• Divergent boundaries createrift valleys on land

What is Transform Boundary?

• Area of crust where 2 plates slip pasteach other, moving inopposite

directions.

• Earthquakes are caused when the tension created by the friction of

the plates moving is released along a fault between two plates.

• Crust is NOTcreated or destroyed

Multiple Select

Convergent plate boundaries create which two crustral features?

• rift valley

• fault

• mountain

• volcano

Multiple Select

Divergent boundaries create which two crustal features?

• rift valley

• mid-ocean ridge

• earthquake

• volcano

Multiple Select

Transform boundaries create which two features?

• rift valley

• mountain

• earthquake

• fault

Can ocean basins get bigger?

Ocean basins are the different regions below sea level

- At divergent boundaries, molten rock flows up through
cracks and hardens to create new oceanic crust
- This continuous process is called seafloor spreading

Can ocean basins get smaller?

At convergent boundaries, a dense oceanic plate may collide with a
less dense plate. The more dense plate sinks under less dense plate
and melts in the mantle through the process of subduction.

-This movement can create ocean trenches.

Multiple Choice

Which crustal feature will form in the picture shown?

• mountain

• volcanic island

• mid-ocean ridge

• fault

Multiple Choice

Which statement BEST describes seafloor spreading?

• When two plates separate, the rising magma forms mountain tops as it cools.

• When two plates separate, the rising magma cools and hardens creating a mid-ocean ridge.

Multiple Select

What major forms of evidence are used to support Plate Tectonics? 

Select TWO correct answers. 

• convection currents

• glacier deposits

• seafloor spreading

• fossil and rock evidence

Multiple Choice

Which statement is the best evidence for the conclusion that faults and volcanoes are results of the movement of tectonic plates?

• Volcanoes are most often located in the middle of tectonic plates

• New volcanoes are located near inactive plate boundaries

• Faults and volcanoes existed before there were any tectonic plates

• Faults and volcanoes are often found at tectonic plate boundaries