ECHO SOUNDER. An electronic instrument used to determine the depth oi water 

 by measuring the time interval between the emission of a sonic or 

 ultrasonic signal and the return of its echo from the bottom. 



EDDY. A circular movement of water formed on the side of a main current. 

 Eddies may be created at points where the main stream passes projecting 

 obstructions or where two adjacent currents flow counter to each other. 

 Also EDDY CURRENT. 



EDDY CURRENT. See EDDY. 



EDGE WAVE. An ocean wave parallel to a coast, with crests normal to the 

 shoreline. An edge wave may be STANDING or PROGRESSIVE. Its height 

 diminishes rapidly seaward and is negligible at a distance of one 

 wavelength offshore. 



EMBANKMENT. An artificial bank such as a mound or dike, generally built to 

 hold back water or to carry a roadway. 



EMBAYED. Formed into a bay or bays, as an embayed shore. 



EMBAYMENT. An indentation in the shoreline forming an open bay. 



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. 



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. 



EROSION. The wearing away of land by the action of natural forces. On a 

 beach, the carrying away of beach material by wave action, tidal currents, 

 littoral currents, or by deflation. 



ESCARPMENT. A more or less continuous line of cliffs or steep slopes facing 

 in one general direction which are caused by erosion or faulting. Also 

 SCARP. (See Figure A-1.) 



ESTUARY. (1) The part of a river that is affected by tides. (2) The region 

 near a river mouth in which the fresh water of the river mixes with the 

 salt water of the sea. 



EYE. In meteorology, usually the "eye of the storm" (hurricane); the roughly 

 circular area of comparatively light winds and fair weather found at the 

 center of a severe tropical cyclone. 



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