Earth Forces

​Science Root of the Day:

DO NOW: Write what you think the example words mean in your lab manual.

Extra Credit: Find three additional words that use this root and write them and their definition in your lab manual (6 Points Max)

Lesson 4.2: Forces inside the Earth's Crust

Mount Everest is the Highest mountain on Earth. It's height continues to increase as forces inside the Earth push it up several millimeters Each Year

Multiple Choice

The point beneath Earth’s surface where rock breaks under stress and triggers an earthquake is called the

• syncline.

• footwall

• epicenter

• focus

Multiple Choice

Earthquakes happen every day. Most are too small for humans to notice.

• True
• False

Hotspot

Which part of a graph shows the independent variable?

Multiple Choice

The type of seismic waves that arrive at the surface first and move by compressing and expanding the ground like an accordion are called

• S waves

• P waves

• Surface Waves

• Mercalli waves.

Multiple Choice

The type of seismic waves that shake the ground of the Earth so they roll like the waves of the ocean

• S waves

• P waves

• Surface Waves

• Mercalli waves.

Multiple Choice

Water from rain or melted snow that flows along the earth's surface and into larger bodies of water is called...

• run off

• gully

• rill

• stream

Multiple Choice

The type of seismic waves that arrive at the surface Second and move side to side

• S waves

• P waves

• Surface Waves

• Mercalli waves.

Multiple Choice

According to the graph, which animal has a life span that is longer than a giraffe's but shorter than a lion's?

• Tiger

• Chipmunk

• Camel

• Mouse

Lesson Objectives

• Explain how Stress in the crust changes the Earth's Surface

• Describe the three major types of faults and what happens at them

• Compare and contrast the land features that result from plate movement

How Does Stress change the Earth's Crust?

• The movement of Earth's plates creates forces that can bend and fold rocks

• Stress: a force that acts on a rock to change its shape or volume​

  • Increases with Force

  • Adds Energy to Rock, which is stored until the Rock breaks

• Three types of stress in the Earth change the shape of rock over millions of years

Tension

• Stress force that pulls the crust of the Earth and thins Rock in the middle

• Occurs when two tectonic plates pull apart​

Compression

• Stress force that squeezes rock until it folds or breaks

  • Occurs when two plates come together​ and push into each other

Shearing

• Stress force that pushes a mass of Rock in two opposite directions

• Can cause Rocks to break or slip apart

• changes the shape of the rock

• Occurs when two plates slide against each other​

Match

Match the following types of stress with how they move

• Tension

• Compression

• Shearing

Two Plates Pulling Apart

Two Plates Coming Together

Two Plates Slide against Each Other

• Two Plates Pulling Apart

• Two Plates Coming Together

• Two Plates Slide against Each Other

Multiple Choice

How does Stress change rocks?

• Stress makes rocks more colorful.
• Stress causes rocks to float on water.
• Stress has no effect on rocks.
• Stress adds Energy to rocks, which is stored until the Rock breaks

How do Faults Form?

• Most Faults occur along plate boundaries where the forces of plate motion push/pull the crust so much it breaks

  • When enough stress builds up inside a rock​, it will break & create a fault

• Three types of Faults

  • Normal

  • Reverse

  • Strike-slip

Normal Faults

• The Fault cuts through rock at an angle so one block of rock sits over the fault & the other sits under the fault

  • Hanging Wall: the rock over the fault in a normal fault

  • Foot Wall: The Rock that lies under the fault​

• ​When movement occurs the hanging wall slips downwards

• Occur where tension pulls rock apart​

Reverse Faults

• Has the same structure as a normal fault, but moves in the opposite directions

  • The Hanging wall Moves up, the Foot wall moves down

• Form in areas of compression in the crust

Strike-Slip Faults

• Formed by Shearing

• Rocks slide past each other sideways, with little up or down motion

• When one forms the boundary between two plates, it is a called a Transform Boundary​

Multiple Choice

When two plates move away from each other ________________ faults are created.

• Normal

• Reverse

• Strike-Slip

Multiple Choice

Stress is a(n) ____________   that acts on rock to change its shape or volume.

• Force

• Power

• Scale

• Epicenter

Match

Match the faults to their descriptions

• Normal Fault

• Reverse Faults

• Slip-Strike Fault

Hanging Wall Slides down when tension pulls rocks apart

Hanging Wall Slides up when plates push against each other

Rocks on either side of a fault slid against each other

• Hanging Wall Slides down when tension pulls rocks apart

• Hanging Wall Slides up when plates push against each other

• Rocks on either side of a fault slid against each other

Multiple Choice

The Stress Force that pulls on the crust and thins the rock in the middle is

• Shearing

• Compression

• Tension

• Uplifting

Multiple Choice

The Stress Force that squeezes a rock until it folds or breaks is

• Shearing

• Compression

• Tension

• Uplifting

Multiple Choice

A fault in which the rocks on either side of the fault move sideways past each other is a __________

• Slip-Strike Fault

• Normal Fault

• Hanging Fault

• Reverse Fault

​How Does Plate Movement Create New Landforms

• Changes in the crust occur extremely slowly and are not easy to observe

• Over millions of years, the forces of plate movement can change a flat plain into different features

  • anticlines

  • synclines

  • folded mountains

  • fault-block mountains

  • plateaus

​Folding of the Earth's Crust

• Folds: bends in rock that form when compression shortens and thickens Earth's Crust

  • When the crusts fold, rocks bend without breaking

  • a fold can vary in width

​Anticlines and Synclines

• Anticline: an upward bend in a rock

• Syncline: A downward bend in a rock

• Both Form in areas of compression in the crust

  • anticlines and synclines form when rocks fold over from compression

8th Grade Science Ohio | Lesson 4.2.2

​Stretching the Earth's Crust

• Tension can stretch the Crust and leave Valleys surrounded by high elevations

  • Fault-Block Mountains: Mountains f​ormed by tension

​Uplifting the Earth's Crust

• Plateaus: a large area of flat land elevated high above sea level

  • has many different flat layers

  • Occur when forces in the crust push up large flat pieces of Rock​

Multiple Choice

Tension can cause the formation of Mountains and ________

• Plateaus

• Valleys

• Anticlines

• Sinclines

Multiple Choice

Normal faults occur when two plates ________

• Come together

• Pull Apart

• Slide Against Each Other

Multiple Select

Mark all Correct Answers: Compression Causes the Formation of

• Anticlines

• Synclines

• Plateaus

• Valleys

Multiple Choice

A large Flat area of Land elevated High above Sea level is a(n)

• Anticlines

• Synclines

• Plateaus

• Valleys