Term
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Definition
| Rocks are a mixture of minerals, rock fragments, volcanic glass, organic matter, or other natural material. |
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Term
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Definition
| Rocks formed from cooled or solidified magma. |
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Term
| How are sedimentary rocks formed? |
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Definition
| Sedimentary rocks are formed when eroded sediments are compacted and cemented |
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Term
| How are metamorphic rocks formed? |
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Definition
| Metamorphic Rock - formed when heat and pressure change an existing rock |
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Term
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Definition
The rock cycle is a series of processes in which rocks continuously change from one type to another.
• Heat and pressure change rocks to metamorphic rocks deep underground
Deeper rocks melt into magma then cool to form igneous rock
Particles eroded from rocks form layers of sediment which are pressed together to form sedimentary rock |
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Term
| What are extrusive rocks? |
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Definition
Extrusive rocks are formed from lava at the surface; also called volcanic rocks. These rocks
• Cool quickly
• Have small crystals
Examples:
Pumice: gasses are trapped to form bubbles; floats in water
Obsidian: has lost all of its gasses; also known as volcanic glass |
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Term
| What are intrusive rocks? |
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Definition
Intrusive Rocks are formed from magma below the surface.
• Also called plutonic rocks.
• Intrusive rocks cool slowly and have larger crystals
• Batholiths are the largest of intrusive rocks; often form the bas of mountain ranges. |
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Term
| What is porphyritic rock? |
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Definition
Porphyritic rock begins forming underground and is then forced out.
• Is considered to be partially intrusive and extrusive.
• Visually, one can see fine-grained crystalline material in which larger crystals are embedded |
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Term
| What are some examples of igneous rocks? |
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Definition
• Granite – intrusive and light colored
• Gabbro – intrusive and dark colored
• Rhyolite – extrusive and light colored
• Basalt – extrusive and dark colored |
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Term
| Describe the formation of sedimentary rocks |
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Definition
Pieces of broken rock are eroded and deposited in layers
2. Bottom layers are compacted and cemented by minerals
3. Lithification is the hardening of sediment into rock |
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Term
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Definition
Clastic rock is formed from mineral grains that have been compacted and cemented.
Examples:
• Conglomerate and breccia – large fragments
• Sandstone from sand, siltstone from mud, and shale from clay |
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Term
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Definition
Organic rock is formed from living things or their remains.
• Limestone, coal
Fossils are remains of dead animals or plants |
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Term
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Definition
Peat (roots, bark, spores, etc) are decayed by bacteria, compacted, heated over time.
To become coal, this decaying peat must be buried by sedimentary rock.
Over time, the peat is broken down, water is released, and is transformed into a carbon rich substance.
Varies but 10-20 ft of peat = 1 foot of coal. |
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Term
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Definition
Chemical rock is crystallized from evaporating solutions.
Example: Evaporites are from evaporating water.
Examples: the Great Salt Lake in Utah and the Dead Sea |
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Term
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Definition
Metamorphism is changes in structure, appearance, or composition of rock beneath the surface
• Contact Metamorphism – when magma contacts existing rock
• Regional Metamorphism – happens along plate boundaries |
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Term
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Definition
| Foliated rocks are rocks with grains arranged in parallel bands. Each band is made of a different mineral. Foliated rocks are formed from pressure in one direction. |
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Term
| What are non foliated rocks? |
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Definition
| Non foliated rocks are usually formed from rocks with only one mineral. Pressure is equal on all sides and the mineral grains are usually the same size. |
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