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10 Cards in this Set
- Front
- Back
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Igneous |
Igneous rocks form when molten rock originating from deep within the Earth solidifies. The chemical composition and its cooling rate determine the final type of igneous rock. |
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Intrusive (igneous) |
Form below ground, and tend to be very large because the magma cools slower. Slow cooling means the individual mineral grains have a long time to grow. |
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Extrusive (igneous) |
Form above ground, and tend to be very small because the lava cools fast. Exposure to the relatively cool temperature of the atmosphere or water makes the erupted lava solidify very quickly. |
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Sedimentary |
Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth´s surface. |
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Clastic (sedimentary) |
Are made up of pieces of pre-existing rocks. Pieces of rock loosened by weathering, then transported to some basin or depression where sediment is trapped. If the sediment is buried deeply, it becomes a sedimentary rock. Clastic sedimentary rocks may have particles ranging in size from microscopic clay to huge boulders. |
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Chemical (sedimentary)
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Are formed by chemical precipitation. This process begins with water traveling through rock dissolves some of the minerals, carrying them away from their source. Eventually these minerals are redeposited when the water evaporates away. |
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Organic (sedimentary) |
Biologic sedimentary rocks form from once-living organisms. They may form from accumulated carbon-rich plant material or from deposits of animal shells. |
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Metamorphic |
Metamorphic rocks are rocks that have been substantially changed from their original form. Metamorphic rocks form when rocks are subjected to high heat and high preassure. |
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Foliated (metamorphic) |
Form when pressure squeezes the flat minerals within a rock, so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that preassure was applied. |
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Non- foliated (metamorphic) |
Do not have platy or sheet-like structure. There are several ways that non-foliated rocks can be produced. Some rocks are made of minerals that are not flat. No matter how much preassure you apply, the grains will not align! Another type of metamorphism, occurs when hot igneous rock intrudes into some pre-existing rock. The pre-existing rock is essentially baked by the heat , changing the mineral structure of the rock without the addition of the preassure. |
