Sedimentary Environment - Terrestrial Environments, Coastal Environments, Marine Environments, Continental Shelf Environments, Deep Oceanic Environments, Interpreting The Sedimentary Record
subenvironments surface factors deposits
A sedimentary, or depositional, environment is an area on the Earth's surface, such as a lake or stream, where large volumes of sediment accumulate. All environments of deposition belong to one of three settings: terrestrial, coastal (or marginal marine), and marine. Subenvironments, each with their own characteristic environmental factors and sedimentary deposits, make up a sedimentary environment. For example, streams consist of channel, sand bar, levee and floodplain subenvironments, among others.
Sedimentary environments display great complexity and almost infinite variety. Variations in environmental factors such as climate, latitude, surface topography, subsurface geology, and sediment supply help determine the characteristics of a particular sedimentary environment, and the resulting sedimentary deposits. This entry deals only with typical examples of common environments, with greatly simplified descriptions.
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Water, wind, and ice erode, transport, and deposit terrigenous sediments on land. Geologists recognize five common terrestrial sedimentary environments: stream, lake, desert, glacial and volcanic. Streams are the most widespread terrestrial sedimentary environment. In fact, because they dominate landscapes in both humid and arid climates, stream valleys are the most common landform on Earth. Stre…
Where the land meets the sea, interplay between terrestrial and marine processes causes sedimentary environments to be very complex. In areas where wave energy is low and the tidal range (the difference between high tide and low tide) is also low, terrestrial processes usually dominate. For example, sediments flowing into the sea from a river will form a well-developed delta. If wave energy is hig…
The average continental shelf is about 45 mi (75 km) wide. Shelf sediments generally decrease in grain size with increasing distance from shore. This occurs for two reasons: (1) greater distance from sediment sources and (2) decreasing sediment movement (transport) with increasing water depth. Shelf sediments vary significantly with latitude. At high latitudes, glacial ice flowing into coastal wa…
Seaward of the continental shelves, continental slopes incline more steeply, so relict and modern sediments form deposits called deep-sea fans. These are similar to alluvial fans, but generally consist of sand- to clay-sized particles with little or no gravel. Deep-sea fans form the continental rise, a continuous apron of sediment at the base of the continental slope. …
Geologists associate subenvironments with specific sediment features by observing modern sedimentary environments and the resulting sediments. These features include sediment composition, sediment texture (size, shape and sorting), vertical changes in grain size, and various sedimentary structures such as wave and current ripples, desiccation cracks in mud, plant and animal remains, and bedding th…
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User Comments
10 months ago
amY
So sub environments are just more specific? Fer example: Ocean is the environment but then continental shelf, oceanic ridge, continental margine, etc. are all sub environments. Would that be correct?
about 1 year ago
ummm... is this any different between transsitional or terrestrial, if. so what is transsitional environment??