Instruction 1-1 Structure of the Earth | Plate Tectonics | Earthquakes, Volcanoes, Mountain Building | Geology of California | Summary |
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| Structure of Earth http://scign.jpl.nasa.gov/learn/plate1.htm |
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| CCSTD GR6 Science 1. | |||||||||
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The Earth seems solid beneath your feet, except when you come to a geyser or
volcano or body of water. But it isn't solid all the way through.
The Layers of the Earth Let's start at the surface and move downward.The Crust The uppermost layer, the layer we walk around on, is called the Crust.
It is made up of rock that floated to the surface when the Earth was formed. The Mantle The next layer down is called the Mantle. The Mantle is also divided into two parts, like the Crust. These parts are the Outer (or Upper) Mantle and the Inner (or Lower) Mantel. The Upper Mantel is made up of silicates of iron and magnesium. It is firm on top with liquid rock on the bottom. Scientists often refer to the top part of the Upper Mantle and the Crust together as the Lithosphere. The Lithosphere is the coldest, most brittle of Earth's layers. It floats on the lower, liquid part of the Upper Mantle (the Asthenosphere) like a marshmallow on hot chocolate. Beneath the Upper Mantle lies the Lower Mantle. It is the layer closest to the Earth's Core. The Core The center of the Earth is called the Core. It is a dense metallic ball made mostly of iron, with some nickel. It, too, is made up of two parts: the Outer Core and the Inner Core. The Outer Core begins about 1,800 to 3,200 miles beneath the Earth's surface. It is made up of iron, nickel, sulfur and oxygen. It is cooler than the Inner Core, about 7,200 to 9,032 degrees Fahrenheit, and that’s hot enough that it remains liquid. The Inner Core is about 780 miles thick. It is from 3,200 to 3,960 miles beneath the Earth's surface. It is very hot, about 10,000 degrees Fahrenheit. Although the Inner Core is very hot, the pressure is so great that it remains solid. In addition to iron and nickel, scientists think the Inner Core contains sulfur, carbon, oxygen, silicon and potassium. Because the Inner Core is so hot, it radiates currents of heat upward toward the upper layers. These currents are called convection currents. It is these convection currents that cause the Tectonic Plates on the Earth's surface to move. And it is this movement of Tectonic Plates that causes volcanic eruptions, earthquakes and mountain building. Video Instruction
Experiments for Home and Classroom In this experiment, students construct an edible model of the layers of the Earth. The materials required include marshmallows, butter, Rice Krispies™ and chocolate-shell syrup. Click: http://ology.amnh.org/earth/stufftodo/edible_main.html Intended primarily for Home-School or classroom teachers, these hands-on activities show students the different layers of the Earth. Click: http://www.ofcn.org/cyber.serv/academy/ace/sci/cecsci/cecsci016.html Reading List:
Now let's do Practice Exercise 1-1 (top). Choose printer friendly or online exercises. Printer friendly version requires the Adobe Acrobat Reader 5. Click HERE to obtain a free copy.
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