Science-Geology Planet Earth Chapter 7
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44 terms
Terms | Definitions |
|---|---|
 sphere | round like a ball |
| hemisphere | half of a sphere |
| equator | the imaginary line that runs around the center of the earth which divides it in half |
| rotation | the spinning motion of the earth |
| axis | the imaginary line that runs through the center of the earth from pole to pole |
| revolves | earth travels in a path around sun. We say the "earth revolves around the sun" |
| orbit | a pathway |
| sun's gravity | this force of the sun holds the planets in orbit |
| gravity | the force that holds the earth in its orbit |
| one year | this is how long it takes the earth to revolve around the sun |
| one day | this is how long it takes the earth to rotate once on its axis |
| geologist | a scientist who studies the earth |
| humus | decayed material in the soil |
| crystals | substances that have smooth, flat surfaces that meet in sharp edges or corners |
| characteristics of a mineral | never man-made; same atoms; orderly pattern |
| minerals, humus | substances found in the soil |
| gems | rare and costly minerals (diamonds, rubies, emeralds) |
| topsoil | the upper layer of soil. Supports plant life, it has ingredients plants need to make food |
| subsoil | the soil beneath the top layer that is not as fertile. doesn't support plants. |
| bedrock | a layer of rock beneath the soil that is part of the earth's crust |
| crust | the solid layer of rock that begins beneath the soil and goes down 5-25 miles below the earth's surface |
| mantle | the layer of earth beneath the crust |
| magma | hot, liquid rock |
| core | center of the earth |
| erosion | the wearing away of the earth's topsoil by water and wind |
| delta | a deposit of sand and soil at the mouth of some rivers |
| conservation | using nature's resources wisely |
| natural resource | a material helpful to man which is found in or on the earth |
| sediment | matter that settles to the bottom or sides of a body of water |
| glaciers | massive rivers of ice that move very slowly |
| metamorphic rock | this main group of rocks seems to have been changed by heat or pressure |
| shale | this sedimentary rock is formed from mud or clay |
| marble | this metamorphic rock may start as limestone |
| limestone | this sedimentary rock is made from the shells of sea creatures |
| conglomerate | this sedimentary rock contains pebbles or cobbles |
| sandstone | this sedimentary rock is made of sand that is pressed down under the ocean |
| igneous, sedimentary, metamorphic | these are the three main types of rocks |
| marble | this metamorphic rock can be highly polished and is used to make statues and special buildings |
| sedimentary rock | this category of rocks is formed when sediment is pressed together under the earth so that it hardens |
| slate | this metamorphic rock may begin as shale |
| limestone | chalk is the unhardened form of this sedimentary rock |
| obsidian | Indians used this rock to make arrow heads |
| shale | this is the most common sedimentary rock |
| igneous | this word means "firey" |
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