Regional Geology

Depositional environment is a geographical and/or geomorphic area, which can be defined in terms of physical, biological, chemical, or geomorphic variables. Therefore, a depositional environment is a geomorphic unit in which deposition happens. Such a place of deposition is characterized by a unique set of physical, biological, and chemical change.
The depositional environments processes control how sediment is transported and deposited, what chemical modification it undergoes, and what kind of organisms live in and affect the sediment. The processes result in the characteristic and distinctive sedimentary deposits typical of each environment by which we recognize and identify them.
There are three general depositional environments: continental, shoreline and marine.
1. Continental environments.
- Alluvial/Fluvial – sedimentary environment associated with a river, i.e. river channel, channel margins or borders, flood plain,
- Desert – sediments formed by combination of wind action and river action (usually intermittent). Little organic activity.
- Lake environment – in inland bodies of fresh or seawater – environment controlled by shallow waves and moderate currents.
- Glacial - controlled by dynamics of moving ice sheets in cold climates.

2. Shoreline environments
-  Deltaic environments - sedimentary environments where rivers enter lakes or oceans.
- Tidal flat environment – environment where extensive areas are exposed at low tide – dominated by tidal currents.
- Beach environments – controlled by strong waves approaching and breaking on the shore. Strips and sand and gravel laid down by wave action.

3. Marine environments.
- Continental shelf - environments in shallow waters of continental shores. Sedimentation controlled by relatively gentle currents. Clastic or chemical sediments.
- Continental margin – environment transitional between continental shelf and deep sea environments. Deep water environment where sediments are deposited by turbidity currents.
- Organic reefs – carbonate structures formed by carbonate secreting organisms built up on continental shelves or oceanic volcanic islands.
- Deep sea environments - floors of deep oceans, far from continents. Quiet waters disturbed only occasionally by deep currents. Includes deep trenches in oceans along subduction zones and abyssal plains built up of turbidity currents traveling far from continental margins.

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