.TOURING
COLORADO GEOLOGY
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.TOURING COLORADO GEOLOGY |
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| GLOSSARY | ||
| batholith | a large discordant pluton with an outcropping area greater than 100 square kilometers | |
| boulder | particles greater than 256 mm in size | |
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cirque | a large bowl-shaped hollow carved out of a mountain by a glacier |
| clast | a rock/mineral fragment | |
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clastic sedimentary rock | a sedimentary rock composed of fragents of rocks/minerals (clasts) |
| clay | particles less than 1/256 mm in size | |
| coarse-grained | grain sizes greater than 2 mm | |
| cobble | particles ranging in size from 64 to 256 mm | |
| concordant | parallel to bedding planes, rock layers, or foliation | |
| discordant | not parallel to bedding planes, rock layers, or foliation | |
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dome | a smoothly rounded rock exposed mountain usually formed by the process of exfoliation |
| dyke | a discordant, planar, intrusive igneous body (contrast with sill) | |
| era | major subdivision of the geologic time scale (e.g., Paleozoic, Mesozoic, Cenozoic) | |
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erratic | boulder transported by a glacier and deposited some distance from its source |
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exfoliation | the peeling away of rock layers from the outer surface of a large rock |
| extrusive rock | an igneous rock formed at or near the earth's surface | |
| evaporite | ||
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fault | a break in the rock layers where movement has occurred. |
| felsic | silica-rich igneous rock (light colored) | |
| ferromagnesian | minerals containing iron and magnesium (usually dark-colored) such as biotite, hornblende, augite, and olivine. | |
| foliated/foliation | ||
| glacier | a large, permanent mass of ice, formed on land and which moves due to its own weight | |
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igneous | a rock formed from the cooling down and solidification of magma. |
| intrusive | an igneous rock formed below the earth's surface | |
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joint/jointing | a fracture or crack in rock with no displacement |
| mafic | ferromagnesian rich igneous rock (dark colored) | |
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metamorphic | a rock which has been altered due to pressure and/or temperature. |
| migmatized | a mixture of igneous and metamorphic rocks | |
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mineral | a naturally occurring, inorganic, crystalline solid that has a definite chemical composition. |
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moraine | a body of till deposited by a glacier |
| mylonitized | ||
| non-foliated | ||
| organic sedimentary rock | rock composed primarily of plant or animal remains | |
| pebble | particles ranging in size from 2 to 64 mm | |
| pegmatite | extremely coarse-grained igneous rock | |
| pluton | body of igneous rock formed below the earth's surface | |
| porphyry/porphyritic | an igneous rock with large crystals enclosed in a fine matrix | |
| Pre-Cambrian | the period of time prior to the Paleozoic Era. Rocks older than about 590 million years. | |
| ptygmatic fold | ||
| rock | a naturally formed material composed of one or more minerals. | |
| sand | particles ranging in size from 1/16 to 2 mm | |
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sedimentary | rock formed from the lithification of any type of sediment, precipitation from solution, or consolidation of the remains of plants or animals. |
| shear/sheared/shearing | ||
| silt | particles ranging in size from 1/256 to 1/16 mm | |
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till | unsorted chaotic deposit of rocks deposited by a glacier |
| weathering | processes that change rock at or near the earth's surface. | |
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xenolith | foreign rock fragment "floating" in an igneous rock |
Updated 04/24/03.
