and, therefore, the rock types that will be formed after lithification , if the sediment is preserved in the rock record. - Locations where sediment accumulates. They differ in: o Chemical, physical, and biological characteristics. o Sediment delivery, transport, and depositional conditions.
o Energy regime. - Environments include: o Terrestrial o Coastal o Marine - Terrestrial Environments—deposited above sea level. o Glacial environments—due to movement of ice. Ice carries and dumps every grain size. Creates glacial till; poorly sorted gravel, sand, silt, and clay. o Mountain stream environments. Fast-flowing water carries large clasts during floods. During low flow, these cobbles and boulders are immobile. Coarse conglomerate is characteristic of this setting. o Alluvial fan—sediments that pile up at a mountain front. Rapid drop in stream velocity creates a cone-shaped wedge. Sediments become conglomerate and arkose o Sand-dune environments—wind-blown, well-sorted sand – aeolian deposition . Aeolian deposition pertain to wind activity. Winds may erode , transport, and deposit materials and are effective agents in regions with sparse vegetation , a lack of soil moisture and a large supply of unconsolidated sediments . Dunes move according to the prevailing winds.
Result in uniform sandstones with gigantic cross beds. o River environments—channelized sediment transport. Sand and gravel fill concave-up channels. Fine sand, silt, and clay are deposited on nearby flood plains. o Lake—large ponded bodies of water. Gravels and sands trapped near shore. Well-sorted muds deposited in deeper water. o Delta—sediment piles up where a river enters a lake Often topset, foreset, bottomset geometry A river delta is a landform that forms from deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean , sea , estuary , lake , reservoir , or (more rarely) another river that cannot carry away the supplied sediment. - Marine delta environments—deposited at sea level o Delta—sediment accumulates where a river enters the sea. Sediment carried by the river is dumped when velocity drops. Deltas grow over time, building out into the basin. Much more complicated than simple lake deltas. Many sub-environments present - Marine environments—deposited at or below sea level. o Coastal beach sands—sand is moved along the coastline. Sediments are constantly being processed by wave action. A common result? Well-sorted, well-rounded medium sand. Beach ripples often preserved in sedimentary rocks. o Shallow-marine clastic deposits—finer sands, silts, muds.
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- Plate Tectonics