SHKEHP TRAWL 



the crests move closer together, and since the 

 energy between crests remams relatively fixed, 

 the waves can become higher near shore. 



These eft'ects are evidenced in the initial de- 

 crease in height of the incoming wave, then an 

 increase in height as the wave comes into shore. 



shoaling coefficient — The ratio of the height of 

 a wave in water of any depth to its height in 

 deep water, with the effect of refraction elim- 

 inated. Sometimes called shoaling factor or 

 depth factor. (61) 



shoaling effect — The alteration of a wave proceed- 

 ing from deep water into shallow water. See 

 shoaling. 



shoaling factor — See shoaling coefficient. 



shoal patches — Individual and scattered eleva- 

 tions of the bottom, with depths of 10 fathoms 

 or less, but composed of any material except 

 rock or coral. 



shoal reefs — Bank reefs; also irregular reef 

 patches among submerged shoals of calcareous 

 detritus. (2) 



shock crack — See concussion crack. 



Shoran — A precise short-range electronic naviga- 

 tion system wliich uses the time divergence of 

 pulse-type transmission from two or more fixed 

 stations. (This term is- derived from the words 

 "s^ort-range navigation.") (63) 



shore — The narrow strip of land in immediate 

 contact with the sea, including the zone between 

 high and low water lines. (^See figure for shore 

 profile.) 



shore clearing — See shore lead. 



shoreface — The narrow zone seaward from the 

 low tide shoreline permanently covered by 

 water, over which the beach sands and gravels 

 actively oscillate with changing wave conditions. 

 (61) {See figure for shore profile.) 



shore ice — 1. The basic form of fast ice. It is a 

 compact ice cover that is attached to the shore 

 and, in shallow water, also grounded. (74) 

 2. (or grounded ice). Sea ice that has been 

 beached by wind, tides, currents, or ice pressure. 

 It is a type of fast ice and may sometimes be 

 rafted ice. (5) 



shore ice belt — See ice foot. 



shore lead — A lead between pack ice and a nar- 

 row fringe of fast ice, or between pack ice and 

 the shore. (74) 



It may be closed by wind or currents so that 

 only a tide crack remains. ( 5 ) 



shoreline — The boundary line between a body of 

 water and the land at high tide (usually mean 

 high water). (68) xS'ee coastline. (<S'ee fig- 

 ure for nearshore current system.) 



shoreline and coastal classification — As sug- 

 gested by F. P. Shepard the following genetic 

 classification has two princiiDal subdivisions. 

 Primary coasts and Secondary coasts; the for- 

 mer representing coasts and shorelines which 

 are essentially the result of the sea resting 

 against a landmass that owes its topography to a 



terrestrial agency, whereas the latter are largely 

 the result of present day marine processes or 

 marine organisms. 



I. Primary (Youthful) Shorelines and Coasts 



A. Land Erosion Coasts — which includes 



ria, drowned glacial erosion, and 

 drowned Karst topography. 



B. Subaerial Deposition Coasts — which in- 



cludes river deposition, glacial deposi- 

 tion plains, wind deposition coasts, 

 and landslide coasts. 



C. Volcanic Coasts — which includes lava 



flow coasts, tephra coasts, and volcanic 

 collapse or explosion coasts. 



D. Shaped by Diastrophic Movements — 



which includes fault coasts, fold coasts, 

 and sedimentary extrusions. 



II. Secondary Coasts (may or may not have 

 been Primary Coasts before bemg shaped 

 by the sea) 



A. Wave Erosion Coasts. 



B. Marine Deposition Coasts — which in- 



cludes barrier coasts, cuspate forelands, 

 beach plains, and mudflats or salt 

 marshes. 



C. Coasts Built by Organisms — which in- 



cludes coral reef, serpulid reef, oyster 

 reef, mangrove, and marsh grass 

 coasts. 

 (52) 



shoreline of emergence — That shoreline result- 

 ing when the water surface comes to rest against 

 a partially emerged sea floor. 



shoreline of submergence — That shoreline 

 produced when the water surface comes to rest 

 against a partially submerged land area. 



shore poljTiya — A polynya along the coast, 

 formed either by current or wind. (74) 



shore profile — The intersection of the ground sur- 

 face with a vertical plane ; may extend from the 

 top of the dune line to the seaward limit of sand 

 movement. (61) /S'ee figure on next page. 



short-crested wave — A wave, the crest length of 

 which is of the same order of magnitude as the 

 wavelength. A system of short-crested waves 

 has the appearance of hills being separated by 

 troughs. (73) 



short wave — Waves imder conditions where the 

 relative depth (water depth/ wavelength) is 

 greater than 0.5, and where the phase velocity 

 is independent of water depth, but dependent 

 upon wavelength. 



short-wave radiation — In oceanography, a term 

 used loosely to distinguish radiation in the visi- 

 ble and near-visible portions of the electromag- 

 netic spectrum (roughly 0.4 to 1.0 micron in 

 wavelength) from long-wave radiation (infra- 

 red radiation). (5) 



shrimp trawl — A bottom trawl ; that is, a bag net 

 with a triangular shaped top and bottom, the 

 open end (base of the triangle) fishes in an oval 

 shape spread laterally by otter boards and ver- 



147 



