A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Ecosystem
An organic community of plants and animals and the physical environment they inhabit, e.g. wetlands, rivers, upland. The ecosystem describes the interactions between soil, climate vegetation and animal life.

Effluent
Water that flows from a wastewater treatment plant after it has been treated. Sometimes applied to any industrial discharge of contaminated water at a point source. See also point source.

Emergent Plants
Aquatic plants that are rooted in river or pond sediments with leaves that are at or above the water surface.

Erosion
The process in which rocks and soil material are worn away by water or wind. Erosion from bedrock may occur because of the presence of abrasive particles.

Esker
A feature of glacial deposition, formed of sands and gravels which occur in elongated and often sinuous ridges. Eskers originate as deposits in meltwater streams beneath ice sheets.

Estuary
A place where fresh and salt water mix, such as a bay, salt marsh, or where a river enters an ocean.

Evaporation
The physical process by which liquid water becomes water vapor, including vaporization from water surfaces, land surfaces (including water rising by capillary action from the soil), and snow fields, but not from leaf surfaces. See also transpiration and sublimation.

Evapotranspiration
The loss of moisture from the combined effects of direct evaporation from land and water surfaces, and transpiration from vegetation.

Extrusive Rocks
Igneous rocks formed from volcanic magma that is extruded at the surface. Rapid cooling results in small mineral grain size. Basalt and rhyolite are extrusive rock types.