EARTH STRUCTURE LESSON
Directions:
Print the Earth Structure reading
comprehension passage and questions (see
below).
Students should read the passage
silently, then answer the questions. Teachers may also use the text as
part of a classroom lesson plan.
Lesson Excerpt
You might think the earth is just a giant ball made of rock and soil. On the surface, that is true. The crust is the outermost surface of the earth. It is made of soil with a thick layer of rock underneath. Most of the rocks that make up the crust are made of the elements silicon and oxygen. Smaller amounts of aluminum, iron, calcium, and other elements make up the rest. The crust is thicker beneath the continents and thinner under the oceans. The thickness of the crust varies from five to ten kilometers thick under the oceans, to between twenty and seventy kilometers thick beneath the continents. Underneath the rocky crust, the earth is very different.
Underneath the crust lies the earth's mantle. This layer of the earth is about 2,900 kilometers thick. High temperatures (2800 – 3200 degrees Celsius) melt the rocks of the mantle, forming a substance called magma. This thick, gooey layer has a texture like thick oatmeal. When magma reaches earth's surface, like when a volcano erupts, it is called lava.
Continued...
Earth Structure
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Includes reading passage, questions,
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