The Earth System http :// teachertube.com/viewVideo.php?video_id=249452

1. The Earth Systemhttp://teachertube.com/viewVideo.php?video_id=249452 After this lesson you will be able to identify the main parts of the Earth system and describe how constructive and destructive forces change Earth.

2. Vocabulary • System • Energy • Atmosphere • Geosphere • Hydrosphere • Biosphere • Constructive force • Destructive force

3. What are the main parts of the Earth system? • The Grand Canyon is made up of different parts. Rock forms the canyon walls. Water flows through the canyon in the form of a river, which carves away the rock. Animals such as deer drink the river’s water. And air fills the canyon, allowing the animals to breath. • All these parts work together. So the environment of the Grand Canyon can be thought of as a system. • A system is a group of parts that work together as a whole.

4. Earth as a system • The Earth system involves a constant flow of matter through different parts. For example, you may know that in the water cycle, water evaporates from the ocean, rises into the atmosphere, and then falls from the sky as rain. • The rainwater then flows into and over Earth, and then back into the ocean.

5. Earth as a system • You might be surprised to learn that rock, too, cycles through the Earth system. For example, new rock can form from molten material inside Earth called magma. This material can rise to the surface and harden on land to form new rock. The new rock can erode into small pieces. The pieces can be washed into the ocean, where they may sink to the bottom as small particles, or sediment. If enough of the small particles collect, the weight of the sediment can crush all the particles together. The particles can then be cemented together to form new rock. The flow of rock through the Earth system is called the rock cycle. • The constant flow, or cycling, of matter through the Earth system is driven by energy. Energy is the ability to do work. The energy that drives the Earth system has two main sources: heat from the sun and heat flowing out of Earth as it cools.

6. Parts of the Earth system • Earth contains air, water, land, and life. Each of these parts forms its own part, or “sphere.” • The Earth system has four main spheres: the atmosphere, the hydrosphere, the geosphere, and the biosphere. As a major source of energy for Earth processes, the sun can be considered part of the Earth system as well. • Each part of the Earth system can be studied separately. But the four parts are interconnected. • One of the most important parts of the Earth system is-you! Humans greatly affect the air, water, land, and life of Earth. For instance, the amount of paved land, including roads and parking lots, in the United States is now larger than the state of Georgia.

7. Atmosphere • Earth’s outermost layer is a mixture of gases-mostly nitrogen and oxygen. It also contains dust particles, cloud droplets, and the rain and snow that form from water vapor. • It contains Earth’s weather, and is the foundation for the different climates around the world. • Earth’s atmosphere is the relatively thin envelope of gases that forms Earth’s outermost layer.

8. Geosphere • Nearly all of Earth’s mass is found in Earth’s solid rocks and metals, in addition to other materials. • Earth’s geosphere has three main parts: a metal core, a solid middle layer, and a rocky outer layer.

9. Hydrosphere • About three quarters of Earth is covered by a relatively thin layer of water. Earth’s water can take the form of oceans, glaciers, rivers, lakes, groundwater, and water vapor. • Of the surface water, most is the salt water of the ocean. Only a tiny part of the hydrosphere is fresh water that is drinkable by humans. • The hydrosphere contains all of Earth’s water.

10. Biosphere • Life exists at the tops of mountains, deep underground, at the bottom of the ocean, and high up in the atmosphere. • In fact, life exists in all kinds of conditions. But life as we know it cannot exist without water. The parts of Earth that contain living organisms make up the biosphere.

11. Feedback within a system • For years, the ice in glaciers at Glacier National Park in Montana has been melting. The melting is caused by rising temperatures. As the volume of ice in the glaciers has decreased, the land around the glaciers has become warmer. The warmer land melts the glaciers even faster. • Melting of the glaciers in Glacier National Park is an example of a process called feedback. When feedback occurs, a system returns-or feeds back-to itself data about a change in the system.

12. Feedback within a system • In Glacier National Park, the ground around the melting glaciers feeds back warmer temperatures to the glaciers. Feedback can increase the effects of a changer, as in the case of warming glaciers, or slow the effects down. • Feedback demonstrates how changes in one part of the Earth system might affect the other parts. For example, the feedback of melting glaciers affects the geosphere (the ground), hydrosphere (glaciers), and atmosphere (climate).

13. How do constructive and destructive forces change Earth? • Suppose you left a movie camera running in one spot for the next 100 million years and then you watched the movie in fast motion. • You would see lands forming and mountains rising up-but you would also see them eroding back and down again. • Lands are constantly being created and destroyed by competing forces.

14. Constructive forces • The Himalayas are Earth’s highest mountains. But rock in the Himalayas contains fossils, or remains, of ocean animals such as ammonites. How could creatures that once lived at the bottom of the sea be found at the top of the world? • The Himalayas are the result of the collision of two sections of Earth’s lithosphere, or Earth’s top layer of stiff, solid rock. This layer is broken into huge pieces, or plates, that move slowly over Earth. The slow movement of Earth’s plates is called plate tectonics.

15. Constructive forces • The Himalayas are the result of the collision of the plate that carries India with the plate that carries China. Over millions of years, as these plates collided, their edges were squeezed slowly upward. This process lifted up the ocean floor and formed the Himalayas. • Forces that construct, or build up, mountains are called constructive forces. Constructive forces shape the land’s surface by building up mountains and other landmasses. Volcanoes build up Earth’s surface by spewing lava that hardens into rock. Earthquakes build landmasses by lifting up mountains and rock.

16. Destructive forces • While the Himalayas are being built up, they are also being torn down. Ice, rain, wind, and changing temperatures tear the rock apart. This process is called weathering. After the rock is torn apart, gravity pulls it downward. Eventually, rivers and streams carry away most of the eroded material. • Because forces such as ice, rain, wind, and changing temperatures wear down, or destroy, landmasses, they are called destructive forces. • Destructive forces destroy and wear away landmasses through processes like erosion and weathering. Erosion is the wearing down and carrying away of land by natural forces such as water, ice, or wind.