Spongy chert mass (Skyline Caverns, Front Royal, Virginia, USA) 2 : 無料・フリー素材/写真
Spongy chert mass (Skyline Caverns, Front Royal, Virginia, 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 |
|---|---|
| 説明 | Chert mass in a cave in Virginia, USA.Skyline Caverns is developed in structurally tilted carbonates (mixed dolostones and limestones) of the Rockdale Run Formation (Beekmantown Group, Lower Ordovician).The moderately large, dark-speckled structure shown above is a spongy-textured chert mass in carbonate host rock present in the high wall/ceiling of a Skyline Caverns cave passage. Chert is a cryptocrystalline, quartzose sedimentary rock that can have a biogenic or chemical origin. Many chert occurrences in carbonate rocks are in the form of rounded to subrounded to irregularly-shaped, solid nodules. The spongy chert shown above may be the result of partial chertification of the host rock, or it may have formed by groundwater corrosion during dissolutional cave passage formation. I have encountered ratty-looking chert masses in other caves (e.g., Mammoth Cave in Kentucky), so the latter explanation may be accurate here (?).Locality: Skyline Caverns, Front Royal, central Warren County, northern Virginia, USA |
| 撮影日 | 2016-05-12 10:57:00 |
| 撮影者 | James St. John |
| タグ | |
| 撮影地 |