Delta

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.