table iceberg — See tabular iceberg. 



tableknoll — A knoll with a comparatively 

 smooth, flat top. (62) 



tablemount — A seamount having a compara- 

 tix'ely smooth, flat top. (62) 



table reef — A small isolated reef, with or without 

 islands, which has no lagoon. (2) 



tabular iceberg — (or 'barrier iceberg, table ice- 

 berg). A flat-topped iceberg showing horizon- 

 tal fim-snow layers, usually calved from an ice- 

 shelf formation. (74) 



Newly formed tabular icebergs liave nearly 

 vertical sides and flat tops. In the antarctic 

 where they are most numerous, tabular icebergs 

 may be tens of miles wide, up to 100 miles long, 

 and as much as 1,000 feet thick with about 100 

 feet exposed above the sea surface. In the arc- 

 tic, the large icebergs of this type are called ice 

 islands, but they are considerably smaller than 

 the largest of the antarctic variety. (5) 



tail wind — See crosswind, following wind. 



talus — 1. A slope. 



2. (also called scree). The debris at the foot 

 of a cliff or slope, particularly that ac&umulated 

 as a result of gravitational roll or slide. 

 (68) 



tangential stressses — The components of the 

 stress tensor which are tangential to the faces 

 of the fluid element. (5) 



tangue — Very fine calcareous silt and clay derived 

 from banks of coquina limestone and which is 

 deposited in estuaries and along the coast of the 

 Bay of Biscay. (2) 



tape gage — A tide gage which consists essen- 

 tially of a float attaclied to a tape and counter- 

 poise. (50) 



target strength — A measure of the reflecting 

 power of the tai'get. The ratio, in decibels, of 

 the reradiated sound (target echo) measured one 

 yard from the target to the sound incident on 

 the target. 



taut-wire mooring — A mooring arrangement in 

 which a submerged float provides the upward 

 force necessary to maintain the system in a fixed 

 position witli reference to the sea bottom. Taut- 

 wire moors may be single, double, or multipoint 

 according to design requirements of the system 

 and the speed and variability of the ambient 

 currents. 



tectonics — The study of origin and development 

 of the broad structural features of the earth. 



telementry — The study and technique involved in 

 measuring a quantity or quantities in place, 

 transmittnig this value to a station, and there 

 interpreting, indicating, or recording the 

 quantities. 



telescoped ice — See rafted ice. 



telluric current — (or earth current). Natural 

 electric currents that flow on or near the earth's 

 surface in large sheets. Methods have been de- 

 veloped for using these currents to make resistiv- 

 ity surveys. 



temperature — In general, the degree of hotness or 

 coldness as measured on some definite tempera- 

 ture scale by means of any of various types of 

 thermometers. (5) 



temperature inversion — In oceanography, a layer 

 in which. temperature increases with depth. 



temperature-salinity diagram — (or T-S dia- 

 gram, T-S curve, T-S relation). The plot of 

 temperature versus salinity data of a water col- 

 umn. The result is a diagram which identifies 

 the water masses within the column, the col- 

 umn's stability, and indicates the at value, and 

 allows an estimate of the accuracy of the tem- 

 perature and salinity measurements. 



temperature scale — (or thermom-etric scale). A 

 graduated scale for measuring the temperature 

 of matter, usually based on the freezmg and 

 boiling points of pure water at standard atmo- 

 spheric pressure. The temperature scales most 

 commonly used are the Celsius (centigrade) 

 scale, the Kelvin (or absolute) scale, and the 

 Fahrenheit scale. 



temporary anchorage — See anchorage. 



tension crack — See strain crack, shear crack. 



tented ice — Pressure ice in which two ice floes 

 have been pushed into the air, leaving an air 

 space underneath. (5) 



tent fish — See Alexander's acres. 



tenting — The vertical displacement upward of ice 

 under pressure to form a flatsided arch with a 

 cavity beneath. ^S'ee bending, rafting. (68) 



tephra — A collective term for all clastic volcanic 

 materials which during an eruption are ejected 

 from a crater or from some other type of vent 

 and transported through the air, including vol- 

 canic dust, ash, cinders, lapilli, scoria, pumice, 

 bombs, and blocks. (2) 



Teredo — A genus of molluscan borers. Also the 

 common name of the animal. See shipworm. 



terrace — A bench-like structure bordering an 

 undersea feature. (62) 



162 



