FAULT COAST 



bique Channel and the Red Sea are examples of 

 graben, fault erabayment, fault trough, or rift 

 valley fault blocks. 



fault coast — (or fault scarp coast). A straight 

 coast formed by a fault, consisting of a sea- 

 ward facing escarpment and a downthrown 

 block below sea level. (2) 



fault embayment — See fault block. 



fault line — See fault. 



fault-line coast — See wave-straightened coast. 



fault scarp — See escarpment. 



fault scarp coast — See fault coast. 



fault trough — See fault block. 



fault zone — See fault. 



fauna — The animal population of a particular lo- 

 cation, region, or period. 



feather star — See crinoid. 



fecal pellet — (or castings). Excrement of ma- 

 rine anijnals frequently found in sediments. 

 When fossilized they are often called coprolites, 

 which may also connote a larger size. (2) 



feeder beach — An artifically widened beach 

 serving to nourish downdrif t beaches by natural 

 littoral currents or forces. (61) 



feeder channels — Channels parallel to shore 

 along which feeder currents flow before con- 

 verging to form the neck of a rip current. See 

 also feeder current. 



feeder current — (or rip feeder current). The 

 current which flows parallel to shore before 

 converging and forming the neck of a rip cur- 

 rent. (73) {See figure for nearshore cur- 

 rent system.) 



feeling bottom — The action of a deepwater wave 

 on running into shoal water and beginning to 

 be influenced by the bottom. ( 5 ) 



Fermat's principle — The principle which states 

 that the path along which electromagnetic ra- 

 diation travels between any two points will be 

 that path for which the elapse time for the 

 travel is a minimum. (5) See multipath 

 transmission. 



fetch — 1. {?i\s,o cdJA^A generating area). An area 

 of the sea surface over which seas are generated 

 by a wind having a constant direction and speed. 

 2. Tlie length of the fetch area, measured in 

 the direction of the wind in which the seas are 

 generated. 



fetch length — The horizontal distance (in the di- 

 rection of the wind) over which a wind having 

 a constant direction and sj^jeed, generates a sea. 



fiard — A Swedish term for a glacially formed 

 drowned valley with low glaciated sides which 

 occurs in lowland regions. Fiards are shorter 

 and shallower than fiords. (2) 

 fibrous ice — See acicular ice. 



fibrous sponge — A sponge in which the internal 



skeletal elements are composed of spongin fibers. 



The commercial sponges are of this type. 



fiducial point — A pomt (or line) on a scale used 



for reference or comparison purposes. In the 



calibration of oceanographic thermometers, for 

 example, the fiducial points are 100°C (212°F) 

 and 0°C(32°F), which correspond to the boil- 

 ing point and ice point at standard pressure (760 

 millimeters of mercury). (5) 



field ice — 1. A general term used for all types of 

 sea ice except newly-formed ice. 

 2. An obsolescent term for consolidated ice. 



field of ice — See ice field. 



figure of merit — The allowable transmission loss 

 between a sonar and a target. 



filling — In meteorology, an increase in the central 

 pressure of a pressure system on a constant- 

 height chart, or an analogus increase in height 

 on a constant-pressure chart; the opposite of 

 deepening. The term is commonly applied to a 

 low rather than to a high. ( 5 ) 



film badge — A pack of photographic film used for 

 approximate measurements of radiation expo- 

 sure for personnel monitoring purposes. The 

 badge may contain two or three films of differ- 

 ing sensitivity, and it may contain a filter -which 

 shields part of the film from certain types of 

 radiation. (70) 



filter — In ocean-wave forecasting, a set of formu- 

 las that define the particular wave frequencies 

 and directions in the fetch area which are of 

 significance at the point of forecast. (5) 



filtering effect — In wave hydrodynamics, the dif- 

 ferential damping of pressures or of vertical 

 oscillation of water particles with increasing 

 depth, depending upon the wave period. At any 

 given depth longer waves are damped less than 

 shorter waves. 



filtration method — A technique used in the 

 quantitative estimation and identification of 

 jDlanktonic organisms. Organisms, usually 

 phytoplankton, are removed from water by fil- 

 tration and retained on the surface of the filter. 

 The organisms can then be counted or identified 

 by microscope after suitable preservation and 

 staining of the organisms and subsequent clear- 

 ing (making transparent) of the filter. 



fines — The silt and clay fraction of a sediment. 



fiord — (also spelled fjord). A narrow, deep, 

 steep-walled inlet of the sea, formed either by 

 the submergence of a mountainous coast or by 

 entrance of the sea into a deeply excavated gla- 

 cial trough after the melting away of the gla- 

 cier. A fiord may be several hundred fathoms 

 deep and often has a relatively shallow sill of 

 rock or gravel across its entrance. (2) See 

 fiard. 



fiord ice — Winter ice formed in a fiord. (59) 



fire body — See pyrosome. 



fire cylinder — See pyrosome. 



fireworm — A luminescent marine worm mainly in 

 the Bermuda area. The swarming of this worm 

 during certain phases of the moon creates 

 luminescent displays. (23) 



62 



