I will know:

1. What causes the Earth's surface to move.

2. How the layers interact to create our physical landscape.

Why do I need to know this?

1. To understand how mountains and valleys are formed.

2. To know what causes an earthquake and volcano.

Using the chart, answer:

1. What do you already know about what causes earthquakes & volcanoes?

2. What you want to know about earthquakes & volcanoes?

3. With a partner, find and record one reputable online source of information on volcanoes or earthquakes.

Here we will review the layers of the earth, and how these layers interact to cause the earth's surface to form mountains, rift valleys, mid-ocean ridges and various natural disasters.

Use the attached PDF document to organizer your findings while watching the video. You may have to watch this a few times to get all the information.

Using the chart, answer the following questions:

1. What new information have I learned about the Earth's structure?

2. What new questions to I now want answered?

1. Explain different plate boundaries, their movements and the surface features they create.

2. Identify the types of plate boundaries that create crust and which types destroy crust.

Place the following terms in order starting at the center of the Earth, working your way out to the atmosphere.

Lower Mantle, Outer Core, Inner Core, Oceanic Crust, Asthenosphere, Continental Crust.

What is the function of each layer?

As you review Alfred Wegener's theory of continental drift, create a profile of who Alfred Wegener was. Include:

The objective of his theory (what it proved)

How he proved it.

Example:

Mesosaurs:

*bones from same species found on two continents separated by large sea.

In the early 20th century, German scientist Alfred Wegener published a book explaining his theory that the continental landmasses, far from being immovable, were drifting across the Earth. He called this movement continental drift.

Wegener noticed that the coasts of western Africa and eastern South America looked like the edges of interlocking pieces of a jigsaw puzzle. He was not the first to notice this, but he was the first to formally present evidence suggesting that the two continents had once been connected. Wegener was convinced that the two continents were once part of an enormous, single landmass that had split apart. He knew that the two areas had many geological and biological similarities. For example, fossils of the ancient reptile mesosaurus are only found in southern Africa and South America. Mesosaurus, a freshwater reptile only one meter (3.3 feet) long, could not have swum the Atlantic Ocean. The presence of mesosaurus suggests a single habitat with many lakes and rivers.

Wegener believed that all the continents—not just Africa and South America—had once been joined in a single supercontinent. This huge ancient landmass is known as Pangaea, which means “all lands” in Greek. Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up. Over millions of years, Pangaea separated into pieces that moved away from one another. These pieces slowly assumed their present positions as the continents.

At first, other scientists did not accept Wegener’s theory of continental drift. But scientists now know that the continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics. Over time, tectonic activity changes the Earth’s surface, rearranging and reshaping its landmasses.
The continents are still moving today. Underwater exploration has revealed seafloor spreading. Seafloor spreading is the process of new crust forming between two plates that are moving apart. As the seafloor grows wider, the continents on opposite sides of the ridges move away from each other. North America and Europe, for example, are moving away from each other at the rate of about 2.5 centimeters (1 inch) per year.

As read each of the following types of plate boundaries, you will need to record into your notebook:

1. A simple diagram of the direction of plate movements.

2. What direction the plates are moving.

3. If crust is being destroyed or produced.

4. The impact the plate boundary has on the surrounding environment.

Places where plates are coming apart are called divergent boundaries. As shown in the drawing above, when Earth's brittle surface layer (the lithosphere) is pulled apart, it typically breaks along parallel faults that tilt slightly outward from each other. As the plates separate along the boundary, the block between the faults cracks and drops down into the soft, plastic interior (the asthenosphere). The sinking of the block forms a central valley called a rift. Magma (liquid rock) seeps upward to fill the cracks. In this way, new crust is formed along the boundary. Earthquakes occur along the faults, and volcanoes form where the magma reaches the surface.

Where a divergent boundary crosses the land, a rift valley usually form, which are typically 30 to 50 kilometers wide. Examples include the East Africa rift in Kenya and Ethiopia, and the Rio Grande rift in New Mexico. Where a divergent boundary crosses the ocean floor, the rift valley is much narrower, only a kilometer or less across, and it runs along the top of a mid-oceanic ridge. Oceanic ridges rise a kilometer or so above the ocean floor and form a global network tens of thousands of miles long. Examples include the Mid-Atlantic ridge and the East Pacific Rise.

Plate separation is a slow process. For example, divergence along the Mid Atlantic ridge causes the Atlantic Ocean to widen at only about 2 centimeters per year. Iceland offers scientists a natural laboratory for studying - on land - the processes that occur along submerged parts of a divergent boundary. Iceland is splitting along the Mid-Atlantic Ridge - a divergent boundary between the North American and Eurasian Plates. As North America moves westward and Eurasia eastward, new crust is created on both sides of the diverging boundary. While the creation of new crust adds mass to Iceland on both sides of the boundary, it also creates a rift along the boundary. Iceland will inevitably break apart into two separate land masses at some point in the future, as the Atlantic waters eventually rush in to fill the widening and deepening space between.

Places where plates slide past each other are called transform boundaries. Since the plates on either side of a transform boundary are merely sliding past each other and not tearing or crunching each other, transform boundaries lack the spectacular features found at convergent and divergent boundaries. Instead, transform boundaries are marked in some places by linear valleys along the boundary where rock has been ground up by the sliding. In other places, transform boundaries are marked by features like stream beds that have been split in half and the two halves have moved in opposite directions.

At the Queen Charlotte Fault, the North American Plate is moving southeast and the Pacific Plate is moving northwest relative to one another. They move past each other, with many earthquakes along the transform boundary marking their passage, including the largest earthquake ever recorded in Canada (1949, magnitude 8.1). In California, the San Andreas Fault is a similar transform plate boundary where, again, the Pacific Plate and the North American Plate are slowly sliding past each other.

Although transform boundaries are not marked by spectacular surface features, their sliding motion causes lots of earthquakes. As the plates move in opposite directions, they sort of get stuck on each other and tension builds. The stress of plates move in opposite directions can build over hundreds of years, until the plates finally release past each other, in a violent earthquake. This is like ripping open large zipper. Off the coast of British Columbia the risk is high that a large scale earthquake will hit the region. The last known occurrence of a major earthquakes dates back the year 1700, as told in the history of the local First Nations.

Places where plates crash or crunch together are called convergent boundaries. Plates only move a few centimeters each year, so collisions are very slow and last millions of years. Even though plate collisions take a long time, lots of interesting things happen. For example, in the drawing above, an oceanic plate has crashed into a continental plate. Looking at this drawing of two plates colliding is like looking at a single frame in a slow-motion movie of two cars crashing into each other. Just as the front ends of cars fold and bend in a collision, so do the "front ends" of colliding plates. The edge of the continental plate in the drawing has folded into a huge mountain range, while the edge of the oceanic plate has bent downward and dug deep into the Earth. A trench has formed at the bend.

All that folding and bending makes rock in both plates break and slip, causing earthquakes. As the edge of the oceanic plate digs into Earth's hot interior, some of the rock in it melts. The melted rock rises up through the continental plate, causing more earthquakes on its way up, and forming volcanic eruptions where it finally reaches the surface. An example of this type of collision is found on the west coast of South America where the oceanic Nazca Plate is crashing into the continent of South America. The crash formed the Andes Mountains, the long string of volcanoes along the mountain crest, and the deep trench off the coast in the Pacific Ocean.

Are they dangerous places to live?

Mountains, earthquakes, and volcanoes form where plates collide. Millions of people live in and visit the beautiful mountain ranges being built by plate collisions. For example, the Rockies in North America, the Alps in Europe, the Pontic Mountains in Turkey, the Zagros Mountains in Iran, and the Himalayas in central Asia were formed by plate collisions. Each year, thousands of people are killed by earthquakes and volcanic eruptions in those mountains. Occasionally, big eruptions or earthquakes kill large numbers of people. In 1883 an eruption of Krakatau volcano in Indonesia killed 37,000 people. In 1983 an eruption-caused mudslide on Nevada del Ruiz in Columbia killed 25,000 people. In 1976, an earthquake in Tangshan, China killed an astounding 750,000 people. Yes, convergent boundaries are dangerous places to live, but with preparation and watchfulness, the danger can be lessened somewhat.

Individually answer these "quiz" questions:

1. What type of plate boundary destroys crust?

2. What type of plate boundary creates crust?

3. If you live at a convergent boundary, what dangers do you face?

4. Why do earthquakes occur along transform boundaries?

5. What type of rock is located at a divergent boundary?

Now, in your "Buzz Groups," review your answers to the five questions. Revise your answers if your groups decides on a answer different than yours.