Quartz-pebble conglomerate 4 : 無料・フリー素材/写真
Quartz-pebble conglomerate 4 / 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 | (geology department collection, Bowling Green State University, Bowling Green, Ohio, USA; photo provided by Tyler Houck)------------------------------------------------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.Seen here is conglomerate, which 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. 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.This is a quartzose conglomerate, having rounded quartz pebbles and quartz sand. Some conglomerates are feldspathic - they have an abundance of K-feldpar pebbles. Some conglomerates are lithic - they have an abundance of large clasts composed of a variety of rock types. |
| 撮影日 | 2022-03-15 14:23:11 |
| 撮影者 | James St. John |
| タグ | |
| 撮影地 |