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Deltas And Human Activity

Deltas have been important centers of human activity throughout history, in part because of the fertility of the land and easy access to transportation. Many early human civilizations developed on deltas. For example, the Nile River delta has hosted Egyptian cultures for over seven thousand years.

Deltas contain large expanses of wetlands where organic matter rapidly accumulates. Consequently, delta muds are very rich organic in organic materials and make good hydrocarbon source rocks when buried to appropriate depths. Not surprisingly, deltaic deposits contain extensive supplies of coal, oil, and gas. Deltaic sand bodies are also excellent reservoir rocks for mobile hydrocarbons. This combination of factors makes deltas perhaps the most important hydrocarbon-bearing environment on Earth. Due to this economic bonanza, modern and ancient deltas have probably been more throughly studied than any other sedimentary environment.

Deltas are very low relief; most areas are rarely more than a few feet above sea level. Therefore, they contain freshwater, brackish, and saltwater basins with correspondingly diverse, complex ecologies. Minor changes in the elevation of the delta surface can flood areas with water of much higher or lower salinity, so delta ecology is easily impacted by human activities. As indicated above, humans have significantly altered deltas and will continue to do so in hopes of curbing flooding. As a result, we will continue to see accelerated delta retreat, and wetlands destruction, unless humans develop new flood control technologies or new methods for wetlands protection.



Leeder, Mike. Sedimentology and Sedimentary Basins: From Turbulence to Tectonics. London: Blackwell Science. 1999.

Selby, M.J. Earth's Changing Surface. London: Oxford University Press.1985.

Skinner, Brian J., and Stephen C. Porter. The Dynamic Earth: An Introduction to Physical Geology. 4th ed. John Wiley & Sons, 2000.

Thurman, Harold V., and Alan P. Trujillo. Essentials of Oceanography. 7th ed. Englewood Cliffs, NJ: Prentice Hall, 2001.

Clay Harris


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Delta front

—The seaward, gently sloping part of a delta, which is below water level.

Delta plain

—The landward, nearly level part of a delta, some of which is below sea or lake level and some above.

Delta retreat

—Landward migration of a delta due to erosion of older delta deposits.

Distributary channel

—A large channel within a delta, which delivers water and sediment into an ocean or a lake.

Grain size

—The size of a sediment particle; for example, gravel (greater than 2mm), sand (2–1/16 mm), silt (1/16–1/256 mm) and clay (less than 1/256 mm).

Sediment load

—The amount of sediment transported by wind, water, or ice.

Sedimentary environment

—An area on the earth's surface, such as a lake or stream, where large volumes of sediment accumulate.

Tidal range

—Vertical distance between high tide and low tide during a single tidal cycle.

Additional topics

Science EncyclopediaScience & Philosophy: Cyanohydrins to Departments of philosophy:Delta - Delta Abandonment, Delta Destruction, Deltas And Human Activity - Delta construction, Delta morphology