What is the Earth’s SurfaceLike?Would you ever live in a cave on the side of a tall cliff?Imagine looking out your door and finding that you’re highabove the ground. YIKES!But early people did build homes in high rocks.
If you look at a picture of the earth taken from space, what do you see?
Water! ¾ of the earth is covered by water. The oceans are the largest bodies of water. Rivers carry water from the land to the oceans.
What About the Other ¼?Landforms! -Different shapes of land -Includes: mountains, plains, and plateaus
Mountains Landforms that rise at least 600 meters above the land around them.
Plateaus Higher than the land around them, but are flat on the surface
Why Are There Different Landforms? The surface of the earth is ALWAYS changing. Some of these changes happen slowly over time. Other changes happen quickly.
Volcanoes A mountain formed by hardened lava with an opening through which lava, ashes, rocks, and other materials may come out. http://www.youtube.com/watch?v=Bf4iJvrAv- M&feature=related
Active Volcano Magma forms when the heat and pressure melt rocks inside the earth. Volcanoes form when heat and gases cause pressure to build up under the surface of the earth. When enough pressure builds up, the magma forces it way through weak spots, called vents. Then the magma breaks through the surface. When the magma cools, it hardens, which forms the mountain called a volcano.
Violent Eruption Sometimes a volcano erupts with such force that part of the volcanic mountain may be blown to pieces.
Dormant Volcano A volcano that is “sleeping.” It hasn’t erupted in recent times. Inside, the mountain may be building up pressure that will some day be released.
Effects of Volcanoes Volcanoes create new mountains Volcano eruptions can destroy mountains Volcanoes can create new islands
Earthquakes The shaking of the ground caused by rock movement along a fault Fault: a crack in he earth’s cruse along which rocks move.
Tectonic Plates Large sections of rock that make up the earth’s crust. They are always moving. This movement causes cracks in the crust, which are called faults. When the rocks along a fault move, the ground shakes. Most of these earthquakes are not felt by people; however, some earthquakes can cause a lot of damage.
Let’s Review! List three types of landforms found on the earth. Plains Mountains plateaus
How do volcanoes change the surface of the earth? Volcanoes can create new mountains and new islands. They can also destroy parts of mountains.
What causes earthquakes? Earthquakes are cased when the rocks along a fault move and cause the ground to shake.