ISOBATH - A contour line connecting points of equal water depths on a 

 chart . 



ISOVEL PATTERN - See HURRICANE WIND PATTERN. 



ISTHMUS - A narrow strip of land, bordered on both sides by water, that 

 connects two larger bodies of land. 



JET - To place (as a pile, slab, or pipe) in the ground by means of a 

 jet of water acting at the lower end. 



JETTY - (1) (U. S. usage) On open seacoasts, a structure extending into 

 a body of water, and designed to prevent shoaling of a channel by 

 littoral materials, and to direct and confine the stream or tidal 

 flow. Jetties are built at the mouth of a river or tidal inlet to 

 help deepen and stabilize a channel. (2) (British usage) Jetty is 

 synonymous with "wharf" or "pier". See TRAINING WALL. 



KEY - A low insular bank of sand, coral, etc., as one of the islets off 

 the southern coast of Florida, also CAY. 



KINETIC ENERGY (OF WAVES) - In a progressive oscillatory wave, a summa- 

 tion of the energy of motion of the particles within the wave. 



KNOLL - A submerged elevation of rounded shape rising less than 1,000 

 meters from the ocean floor, and of limited extent across the 

 summit. See SEAMOUNT. 



KNOT - The unit of speed used in navigation. It is equal to 1 nautical 

 mile (6,076.115 feet or 1,852 meters) per hour. 



LAGGING - See DAILY RETARDATION (OF TIDES). 



LAGOON - A shallow body of water, as a pond or lake, usually connected 

 to the sea. (See Figures A- 8 and A-9.) 



LAND BREEZE - A light wind blowing from the land to the sea caused by 

 unequal cooling of land and water masses. 



LAND-SEA BREEZE - The combination of a land breeze and a sea breeze as 

 a diurnal phenomenon. 



LANDLOCKED - An area of water enclosed, or nearly enclosed, by land, as 

 a bay or a harbor (thus, protected from the sea). 



LANDMARK - A conspicuous object natural or artificial, located near or 

 on land which aids in fixing the position of an observer. 



LEAD LINE -A line, wire, or cord used in sounding. It is weighted at one 

 end with a plummet (sounding lead). Also SOUNDING LINE. 



A-19 



