| 11. | Basalt is a dark colored extrusive volcanic rock.
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| 12. | It used to be found in fissure veins in the extrusive igneous rhyolite rock.
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| 13. | Some species have extrusive organelles ( trichocysts ).
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| 14. | Extrusive products include rhyolitic ignimbrites along with basalt, andesite, and rhyolite lava flows.
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| 15. | Extrusive igneous rock are dominant above on the eastern slope and on the western slope.
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| 16. | This is an extrusive igneous rock.
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| 17. | As might be expected, they show structures intermediate between those of extrusive and plutonic rocks.
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| 18. | Well-known examples of outcropping trap rock include both intrusive sills and extrusive lava flows.
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| 19. | Hughes Mountain is formed of extrusive rhyolite which joints when it cooled, creating polygonal columns.
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| 20. | Over large areas extrusive rocks lie in flat undisturbed piles on a Cenozoic surface of moderate relief.
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