Dakota Hogback (west of Denver, Colorado, USA) 1 : 無料・フリー素材/写真
Dakota Hogback (west of Denver, Colorado, USA) 1 / 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 | Tilted sedimentary rocks in the Mesozoic of Colorado, USA.The spectacular outcrop shown above is a cross-section through 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 Front Range of the Colorado Rocky Mountains is immediately west of here).The left-to-center portions of this outcrop are principally the Morrison Formation (Kimmeridgian Stage, middle Upper Jurassic, ~150 to 156 Ma), consisting of fluvial (river/floodplain) and lacustrine (lake) deposits, plus reddish-colored paleosol horizons. Dinosaur bones and dinosaur tracks have been found in the Morrison Formation in this area.The center-to-right portions of the exposure are principally the Dakota Sandstone (Albian Stage, upper Lower Cretaceous), dominated by nearshore terrestrial to intertidal to shallow marine quartz sandstone deposits. Dinosaur tracks are common on some Dakota Sandstone bedding planes in this area.Locality: "POGI" (= Point of Geologic Interest), roadcut along the northern side of Interstate 70, immediately east of the Rt. 40 exit (= exit 259), west of Denver, north-central Colorado, USA |
| 撮影日 | 2012-12-16 13:56:08 |
| 撮影者 | James St. John |
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