EM 1110-2-1100 (Change 1)
31 Jul 03
ELEVATION
The vertical distance from mean sea level or other established datum plane to a point on the earth's surface; height
above sea level. Although sea floor elevation below msl should be marked as a negative value, many charts show positive
numerals for water depth.
EL NIO
Warm equatorial water which flows southward along the coast of Peru and Ecuador during February and March of
certain years. It is caused by poleward motions of air and unusual water temperature patterns in the Pacific Ocean, which
cause coastal downwelling, leading to the reversal in the normal north-flowing cold coastal currents. During many El Nio
years, storms, rainfall, and other meteorological phenomena in the Western Hemisphere are measurably different than during
non-El Nio years.
ELUTRIATION
The process by which a granular material can be sorted into its constituent particle sizes by means of a moving
stream of fluid (usually air or water). Elutriators are extensively used in studies of sediments for determining Particle size
distribution. Under certain circumstances wind, rivers and streams may act as elutriating agents.
EMBANKMENT
Fill material, usually earth or rock, placed with sloping sides and with a length greater than its height. Usually an
embankment is wider than a dike.
EMBAYMENT
An indentation in the shore forming an open bay.
EMERGENT COAST
A coast in which land formerly under water has recently been exposed above sea level, either by uplift of the land or
by a drop in sea level.
ENDEMIC
Native or confined to a specific geographic area.
ENERGY COEFFICIENT
The ratio of the energy in a wave per unit crest length transmitted forward with the wave at a point in shallow water
to the energy in a wave per unit crest length transmitted forward with the wave in deep water. On refraction diagrams this is
equal to the ratio of the distance between a pair of orthogonals at a selected shallow-water point to the distance between the
same pair of orthogonals in deep water. Also the square of the REFRACTION COEFFICIENT.
ENTRANCE
The avenue of access or opening to a navigable channel or inlet.
EOLIAN (also AEOLIAN)
Pertaining to the wind, esp. used with deposits such as loess and dune sand, and sedimentary structures like wind-
formed ripple marks.
EOLIAN SANDS
Sediments of sand size or smaller which have been transported by winds. They may be recognized in marine
deposits off desert coasts by the greater angularity of the grains compared with waterborne particles.
EQUATORIAL CURRENTS
(1) Ocean currents flowing westerly near the equator. There are two such currents in both the Atlantic and Pacific
Oceans. The one to the north of the equator is called the North Equatorial Current and the one to the south is called the South
Equatorial Current. Between these two currents there is an easterly flowing stream known as the Equatorial Countercurrent.
(2) Tidal currents occurring semimonthly as a result of the moon being over the equator. At these times the tendency of the
moon to produce DIURNAL INEQUALITY in the current is at a minimum.
A-28
Appendix A Glossary of Coastal Terminology
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