Lithic conglomerate (Newark Supergroup, Upper Triassic-Lower Jurassic; Virginia, USA) 1 : 無料・フリー素材/写真
Lithic conglomerate (Newark Supergroup, Upper Triassic-Lower Jurassic; Virginia, 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 | Conglomerate from the Jurassic of New Jersey, USA. (ex-museum)Sedimentary rocks form by the solidification of loose sediments. Loose sediments become hard rocks by the processes of deposition, burial, compaction, dewatering, and cementation.There are three categories of sedimentary rocks:1) Siliciclastic sedimentary rocks form by the solidification of sediments produced by weathering & erosion of any previously existing rocks.2) Biogenic sedimentary rocks form by the solidification of sediments that were once-living organisms (plants, animals, micro-organisms).3) Chemical sedimentary rocks form by the solidification of sediments formed by inorganic chemical reactions.Most sedimentary rocks have a clastic texture, but some are crystalline.Conglomerate is a siliciclastic sedimentary rock consisting of a mix of large & small grains - it is poorly sorted. The larger grains (pebbles or cobbles or boulders) in conglomerates are rounded to subrounded in shape. Angular to subangular clasts may be present. The finer-grained matrix is usually sand or mud. Most conglomerates were deposited in stream/river environments or alluvial fan environments or some very shallow marine environments.Seen here is a conglomerate with lithic pebbles (rock fragments). Most conglomerates have quartz pebbles.The rock comes from the Newark Supergroup, an Upper Triassic to Lower Jurassic succession of siliciclastics-dominated rocks that fill a series of rift basins. Rift valleys formed during the Triassic, in what is now eastern North America, as the ancient Pangaea supercontinent attempted to break apart. The initial rifting failed, but a subsequent rifting event in the Jurassic was successful.Stratigraphy: Newark Supergroup, Upper Triassic-Lower JurassicLocality: unrecorded/undisclosed site in Virginia, USA-----------------For more info., see:en.wikipedia.org/wiki/Newark_Supergroup |
| 撮影日 | 2022-08-30 16:33:41 |
| 撮影者 | James St. John |
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