What Is Soil?
Soil is a mixture of very small pieces of rock and rotted materials from plants and animals. This rotting plant and animal material, called humus, gives soil its dark...
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What Is Chalk?
Chalk is a soft, white limestone. The chemical composition is calcium carbonate with minor amounts of silt and clay. It was formed from the shells that belonged mostly...
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How Are Mountains Formed?
How Are Mountains Formed? Mountains are created by slow movements in the earth’s crust. In some places, heat and pressure deep inside the earth slowly buckle the...
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What Is at the Center of the Earth?
What Is at the Center of the Earth? By studying earthquakes, scientists have discovered that the inside of the earth is divided into three main parts. First comes a...
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Where Does Sand Come from?
Sand is made from tiny grains of rocks and minerals. Almost every grain of sand was once part of a big rock. Heat and cold caused cracks in the rocks, and wind and...
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