Rippled sandstone (Dakota Sandstone, Lower Cretaceous; Dinosaur Ridge, Colorado, USA) 14 : 無料・フリー素材/写真
Rippled sandstone (Dakota Sandstone, Lower Cretaceous; Dinosaur Ridge, Colorado, USA) 14 / 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 | Rippled sandstone in the Cretaceous of Colorado, USA.This outcrop is at Dinosaur Ridge, which is a section of the Dakota Hogback, a north-south trending ridge of eastward-dipping Mesozoic sedimentary rocks. Triassic, Jurassic, and Cretaceous rocks are present, tilted by Laramide Orogeny uplift during the Cenozoic.The exposure consists of structurally tilted beds of the Dakota Sandstone, a Lower Cretaceous succession of nearshore terrestrial to intertidal to shallow marine quartz sandstone deposits. Dinosaur tracks are common on some Dakota Sandstone bedding planes.The ridges in the picture are symmetrical ripples on a shallow marine sandstone bedding plane. Symmetrical ripple marks only form in shallow water settings where two-directionsal, back-and-forth wave action influences seafloor sediments.Stratigraphy: Dakota Sandstone, Albian Stage, upper Lower CretaceousLocality: eastern side of Dinosaur Ridge, between Interstate 70 and the town of Morrison, west of Denver, north-central Colorado, USA |
| 撮影日 | 2007-07-25 18:25:41 |
| 撮影者 | James St. John |
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