Mud Volcano's margin (29 August 2011) 2 : 無料・フリー素材/写真
Mud Volcano's margin (29 August 2011) 2 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Hot springs are sites where groundwater emerges at the Earth’s surface (or on the seafloor). Hot spring water has to be higher in temperature than the human body (an admittedly arbitrary definition): over 98° Fahrenheit or over 37° Celsius. Geysers are hot springs that episodically erupt columns of water. The highest concentration of geysers and hot springs anywhere is at the Yellowstone Hotspot Volcano in northwestern Wyoming, USA.Mud Volcano is the namesake of Yellowstone’s Mud Volcano Group, on the western side of the Yellowstone River, north of Yellowstone Lake. Historical evidence indicates that, in the 1800s, Mud Volcano was a cinder cone volcano-shaped feature that had impressive mud eruptions. A hydrothermal explosion apparently destroyed much of the cone. What remains is a 7 meter-diameter, subcircular hot spring pool bordered by a high wall on its southern, southwestern, and western sides. Well-developed mudcracks are present along the northern and northeastern edges of the pool. The mud formed by chemical decomposition of rhyolitic volcanic tuffs. Rising volcanic hydrogen sulfide gas (H2S) oxidized above the water table and became sulfuric acid (H2SO4). Published research has shown that microbes also produce sulfuric acid in the Mud Volcano area, by oxidizing elemental sulfur (S). Sulfuric acid is a strong acid and readily altered the rhyolitic rocks, resulting in clay minerals, which became mud when mixed with water. Dark gray wisps in the muddy water represent fine-grained iron sulfide (pyrite). Two energetic vents are present at Mud Volcano - their activity is undercutting the adjacent high wall. In 1998, researchers measured the water here at 187° Fahrenheit (= 86° Celsius), with a pH of 3 (= acidic). |
| 撮影日 | 2011-08-28 15:59:35 |
| 撮影者 | James St. John |
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