4.2 - Why is Plate Tectonics important?

Lesson Purpose

In the last lesson, you learned that the interior of the Earth changed over time to give the planet the unique layering that it currently possesses. In this lesson, you will learn that the surface of the Earth changes as well. The high temperature that caused the differentiation of the Earth's layers continue even today. In a process known as Plate Tectonics, the heat and movement of the mantle floating under the Earth's crust drive the movement of the Earth's crust over its surface. The slow shifting of these tectonic plates explains the shape of our continents as well as mountain ranges and traumatic events like earthquakes.

The outcomes of this lesson are: 1.) To use evidence to explain how the Earth and its atmosphere developed and changed over time; 2.) To explain the basic mechanisms and key pieces of evidence for plate tectonics, and how plate tectonics impacts life on Earth.

Activity 1 - The Solar System & the Earth: Crash Course

Activity Objectives
Crash Course Big History Episode #3. This video provides a review of the key lessons about formation of the Earth and Solar System and the early history of the Earth, and then provides a brief introduction to plate tectonics, the focus of this lesson.

Activity Tasks

Watch the video and try to answer the following questions:
1. 1:20 Why is Pluto no longer considered a planet?
2. 2:08 What does it mean to say that the Sun is a second generation star? How long did it take to form?
3. 4:41 What were some of the materials orbiting the Sun after it formed, and why did the dust begin to stick together (that is, accrete)?
4. 5:57 How long did our Solar System take to get to the form it has today?
5. 7:10 What happened to the heavier metals when the planet formed?
6. 7:27 What happened to the gases that rose up from beneath the Earth’s crust and were released in volcanic eruptions?
7. 8:29 The conditions of the Hadean eon were awful, but they did help make the Earth more chemically complex. How?
8. 9:30 When and why did the oceans form?
9. 9:50 Why is the Earth compared to an egg when the discussion of plate tectonics begins in this video?
10. 12:18 What are some of the benefits of plate tectonic activity?
11. 13:16 Why has our knowledge of planets and solar systems changed in the last 20 years?

The formation of the Sun made possible the formation of our Solar System. The circumstances of the Earth’s formation and its early history created conditions that made life possible on our planet. The fact that the Sun was a second generation star, meaning that a greater diversity of elements was available for the formation of the Earth, is just one of the many results of this process that affected the ability of life to develop on Earth.

Activity 2 - Our Shifting Globe

The movement of the continents, driven by plate tectonics, is critical to understanding the Big History story. Changes to the planet occur really, really slowly. Over very, very long periods of time, the results are dramatic. The movement of the tectonic plates shapes our continents and the land around us. At the same time, the movement of tectonic plates alternately exposes and conceals mineral deposits that we use every day.

Activity Objectives
The surface of the Earth is changing all the time. It’s now possible for scientists to determine how the tectonic plates on the surface of the Earth have moved over time, and write the history of the Earth. Understanding how and why plates move is important for understanding both the Earth’s history and the changing conditions in the biosphere.

Activity Tasks

Watch the video and try to answer the following questions:
1. 1:00 What is a tectonic plate and what are some of the characteristics of the Earth’s plates?
2. 1:38 What special role do oceanic plates play in the story of the Earth?
3. 1:43 What drives the movement of the tectonic plates?
4. 2:43 What causes earthquakes?
5. 3:29 What did the surface of the Earth look like 250 million years ago?
6. 4:16 How long did it take for the Earth to take on the appearance it has today, and how fast did the plates move?

Activity 3 - Claim Testing: Geology and the Earth's Formation

Activity Objectives
You should already be familiar with claims testing from previous lessons. This activity will allow you to review the four claims testers and understand how scientists would investigate claims about plate tectonics.

Activity Tasks

Get into groups of three or four and look at the five claims on this worksheet.
Decide whether each claim is true or false AND justify your choices by thinking about what claim testers you have used to support that claim. To remind you, the claim testers are:
1. Authority
2. Evidence
3. Logic
4. Intuition

Activity 4 - "Why We're all Lava Surfers"

Activity Objectives
Earthquakes and volcanoes happen as a result of plate movements. Both are events that all humans are familiar with, either from actually observing them or seeing them on television or the Internet. This reading draws a connection between these familiar events and the evidence for plate tectonics.

Activity Tasks

Read this article on the real-life evidence for plate tectonics and answer the following questions:
1. Why does Peter Stark call us “lava surfers”?
2. Why are there so many earthquakes in Indonesia?
3. What creates the geysers at Yellowstone National Park?
4. Why does Stark describe the Earth as “new” as he views the volcano?
5. Discuss - If we are all lava surfers, why do some parts of the Earth have relatively “small waves” but other places, like Indonesia, have “big waves”?

Activity 5 - Biography of a Continent

Activity Objectives
The early Earth was an inhospitable place. It wasn’t until the start of the Archaean eon, almost 700 million years after the Earth was created, that rocks formed, which made possible the development of the massive formations we call continents. Although all the continents formed at about the same time, there are important ways in which they differ. In this activity, in groups you will investigate the characteristics of the individual continents, which will help them see the similarities and differences.

Activity Tasks

Get into seven groups. Each group will be assigned one continent. You will be investigating the characteristics and history of your continent - both geological and human. Research and answer the following questions, creating a map from this document highlighting its most important features:
1. What is the origin and meaning of your continent’s name?
2. What tectonic plates make up your continent?
3. When did your continent take the form that it has today?
4. When did your continent arrive at the location it is in today?
5. What landforms, plant life, and animal life are unique to your continent?
6. What processes have given rise to the geological, geographic, and biological features that your continent has today?
Try to track down your own sources of information for this task, but use these three web sources as a starting point:

Challenge Yourself! - Optional Activities

1. Learn how lonely, cold, and distant Pluto got demoted to "dwarf planet" status in 2006.
2. Find out about global earthquake and seismic activity happening right now!
3. In 1960, the most powerful earthquake ever recorded happened near Valdivia, Chile and rated an almost off-the-charts 9.5 on the Richter scale.
4. Visit the volcanoes of Hawaii and experience the beauty of an active lava lake.

TAKE THE QUIZ!