Vitrophyre (Mount Belknap Volcanic Series, Lower Miocene, 18.9 Ma; Marysvale Valley, Piute County, Utah, USA) 2 : 無料・フリー素材/写真
Vitrophyre (Mount Belknap Volcanic Series, Lower Miocene, 18.9 Ma; Marysvale Valley, Piute County, Utah, USA) 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 | Vitrophyre from the Miocene of Utah, USA.This is a sample of rhyolitic vitrophyre (= "glassy rhyolite"), a felsic, glassy-textured, extrusive igneous rock. It is similar to obsidian, but it has small crystals surrounded by black glass. Vitrophyre does not break with the well-developed conchoidal fracture of obsidian. This material occurs at the base of a Miocene-aged ash fall tuff unit. The source volcano is the nearby Red Hills Caldera in the Antelope Range north of Marysvale, Utah.Stratigraphy: basal Red Hills Tuff Member, Mount Belknap Volcanic Series, upper Lower Miocene, 18.9 MaLocality: Black Rock Knob - exposure on the western side of Route 89, 2.2 miles south of Hoover's rest stop (= Deer Creek-Sevier River intersection), southern end of Marysvale Valley (a graben), north of the town of Marysvale, far-northern Piute County, southwestern Utah, USA (38° 28' 40.78" North latitude, 112° 14' 28.17" West longitude)---------------------------------Reference on the geology of the Mount Belknap & Red Hills volcanic successions:pubs.usgs.gov/bul/1468/report.pdf |
| 撮影日 | 2020-11-27 19:27:21 |
| 撮影者 | James St. John |
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