Unit E Section 1 Introduction The Earth's Crust is Constantly Changing
Completion requirements
Section 1: The Earth's crust is constantly changing.
Unit E: Section 1 - Introduction
Figure E.S.1.1 – How do canyons form?
Figure E.S.1.2 – Hoodoos in Drumheller are as much as 7 metres high.
A Changing Earth
If somebody asked you how long it takes for a canyon to form, you might make a reasonable guess of a million years. What of hoodoos? Thousands of years. A glacier moving down a valley? Probably a hundred years. That does not mean all changes on Earth occur slowly.
Landslides, earthquakes, and volcanic eruptions are sudden changes to Earth. These can take days, hours, minutes, or even just seconds; yet, the effects can be catastrophic and the damage observed for many years.
Have you heard someone speak of terra firma to mean solid Earth? Often, we think of Earth as never-changing or, perhaps at best, changing very slowly. This is true much of the time – rocks seem to remain as they are unless disturbed by farmers or road builders. However, other circumstances can lead to sudden and violent changes.
We can understand better all these changes by studying models of Earth’s structure. Scientists use various methods and technologies to predict what is inside Earth, to explain the origin of various landforms, and to measure the changes that occur under and on its surface.
If somebody asked you how long it takes for a canyon to form, you might make a reasonable guess of a million years. What of hoodoos? Thousands of years. A glacier moving down a valley? Probably a hundred years. That does not mean all changes on Earth occur slowly.
Landslides, earthquakes, and volcanic eruptions are sudden changes to Earth. These can take days, hours, minutes, or even just seconds; yet, the effects can be catastrophic and the damage observed for many years.
Have you heard someone speak of terra firma to mean solid Earth? Often, we think of Earth as never-changing or, perhaps at best, changing very slowly. This is true much of the time – rocks seem to remain as they are unless disturbed by farmers or road builders. However, other circumstances can lead to sudden and violent changes.
We can understand better all these changes by studying models of Earth’s structure. Scientists use various methods and technologies to predict what is inside Earth, to explain the origin of various landforms, and to measure the changes that occur under and on its surface.
Figure E.S.1.3 – Turtle Mountain landslide destroys the town of Frank, Alberta in 1903.
Words to Think About:
Check out the word cloud below. It pictures the important words that you are going to learn in this section. Watch for these words, and combinations of these words, as you read. When you see them highlighted, you can click on them to learn more about
what the word means.
You can also visit the course glossary and read definitions for all of these words.
Lessons in This Section
Lesson E1: Structure of Earth
Key Question – What is inside Earth?
Lesson E2: Earth's Violent Crust: Earthquakes and Landslides
Key Question – How do earthquakes and landslides occur?
Lesson E3: Earth's Violent Crust: Volcanoes
Key Question – What are volcanoes?
Lesson E4: Earth's Violent Crust: Then and Now
Key Question – How do we study earthquakes and volcanoes?
Lesson E5: Slow and Steady Change
Key Question – What are weathering, erosion, and deposition?
Reading and Materials for This Section
Science in Action 7
Materials Lists for Unit:
Reading: Pages 352–367
Materials Lists for Unit:
Try It!
Building a Model
This is an activity you can attempt on your own, or you can challenge a friend or family member to try it.
Materials:
This is an activity you can attempt on your own, or you can challenge a friend or family member to try it.
Materials:
- small marble
- balloon
- water
- pail or box with lid
Instructions:
- Secretly place a small marble in an uninflated balloon. Fill the balloon with water and tie it. Place the water balloon in a small pail or box, and cover it with a lid.
- Ask a volunteer to put on a blindfold, but do not tell your volunteer about the water balloon and container.
- Place the container holding the water balloon carefully in the volunteer’s hands. Tell the person he or she can move the container around gently and use his or her ears and hands for help.
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Ask the person to guess what he or she is holding, being as specific as possible without placing his or her hands in the container.
Questions:
Think about the following questions very carefully. Then, type or write your answers. When you have your answers, click the questions for feedback.
Most people depend on their sight when they try to identify something. When you cannot see something directly, the challenge is to use your other senses to determine what it is.
If sight is not available, one very useful sense is sound. Moving the container around generates various kinds of sounds. For example, by shaking the container gently, bouncing sounds might lead the person to believe something soft and rubbery is inside.
Also, using your sense of touch to feel vibrations can give a great deal of information.
Constructing a model without being able to see what you are modelling is extremely difficult. This activity is similar to the challenge scientists have had to determine the structure of Earth. Currently, very few methods of viewing the inside of Earth
are available, yet scientists have some very detailed models from evidence available. Can you think of any instruments or procedures that could help someone guess the contents of the water balloon container without using any methods that involve
sight?