Mudcracks in argillite (Grinnell Formation, Mesoproterozoic, ~1.45 Ga; Glacier National Park, Montana, USA) 5 : 無料・フリー素材/写真
Mudcracks in argillite (Grinnell Formation, Mesoproterozoic, ~1.45 Ga; Glacier National Park, Montana, USA) 5 / 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 | Mudcracks in argillite in the Precambrian of Montana, USA.Mudcracks are diagnostic sedimentary structures indicating subaerial exposure of sediment surfaces, with alternating wet & dry conditions. They are much more common that raindrop imprints, which indicate the same environmental setting. Mudcracks are most likely to occur in fine-grained siliciclastic rocks, fine-grained carbonate sediments, and in some evaporitic successions. Mudcracks are distinctive and easy to identify, but they do vary in appearance. The cracks themselves vary in width, depth, and areal density. Mudcrack polygons also vary in size & shape.Stratigraphy: Grinnell Formation, Belt Supergroup, Mesoproterozoic, ~1.45 GaLocality: low rock wall built along paved trail at Sunrift Gorge, Going to the Sun Highway, Glacier National Park, northwestern Montana, USA |
| 撮影日 | 2008-09-03 15:12:37 |
| 撮影者 | James St. John |
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