BASE STATION 



base station — A geographic position whose ab- 

 §ohite gravity value is known; also the point 

 from which a survey begins. 



In exploration, particularly magnetic or grav- 

 ity surveys, a reference station where quanti- 

 ties under investigation have known values or 

 may be under repeated or continuous measure- 

 ment in order to establish additional stations in 

 relation to it. (2) 



base surge — A cloud which rolls out from the bot- 

 tom of the column produced by a subsurface 

 burst of a nuclear weapon. For underwater 

 bursts the surge is, in effect, a cloud of liquid 

 droplets which has the property of flowing al- 

 most as if it were homogeneous fluid. (63) 



basic rock — In geology, a term for igneous rocks 

 that are comparatively low in silica. 



basin — A dejoression of the sea floor more or less 

 equidimensional in form and of variable extent. 

 (62) 



bastard — A hard massive boulder or rock. Also 

 adjective meaning of abnormal shape or of un- 

 usual composition or proportion. (48) 



bathy — An indicator group in the coded bathy- 

 thermograph message. 



bathyal — Pertaining to ocean depths between 100 

 and 2,000 fathoms (180 and 3,700 meters) ; also 

 to the ocean bottom between those depths, some- 

 times identical with the continental slope en- 

 vironment. {See figure for classification of 

 marine environment.) 



bathyconductograph (BC) — A device to measure 

 the electrical conductivity of sea water at var- 

 ious depths from a moving ship. 



bathymeter — An instrument primarily designed 

 for measuring depth of water. Bathymetric 

 surveys, previously done by lead line, are now 

 performed by using an echo sounder and a pre- 

 cision depth recorder. (35) 



bathymetric — Of or pertaining to bathymetry. 

 (68) 



bathymetric chart — A map delmeatmg the form 

 of the bottom of a body of water, usually by 

 means of depth contours (isobaths). (5) 



bathymetric low — See low (sense 2) . 



bathymetry — The science of measuring ocean 

 depths in order to determine the sea floor topog- 

 raphy. 



bathypelagic — A depth zone of the ocean which 

 lies between depths of 500 and 2,000 fathoms 

 (900 and 3,700 meters). {See figure for clas- 

 sification of marine environment.) 



bathypelagic fish — Any of a variety of oceanic 

 fishes which, at least part of the time, inhabit a 

 depth range between about 500 to 2,000 fathoms 

 (900 to 3,700 meters). Many of these fishes 

 characteristically undergo extensive diurnal ver- 

 tical migrations and are thought to contribute to 

 sound scattering layers in the sea. 



Bathyscaphe — (also spelled Bathyscaph, Bathy- 

 scap ) . A free, manned vehicle for exploring the 

 deep ocean. 



Bathysphere — A spherical chamber in which 

 persons are lowered for observation and study 

 of ocean depths. (68) 



bathythermogram — The record made by a 

 bathythermograph, or a photographic print of 

 this record and accompanying meteorological 

 observations. Now rarely used. (68) 



bathythermograph — (abbreviated BT). A de- 

 vice for obtaining a record of temperature 

 against depth (strictly speaking, pressure) in 

 the ocean, from a ship underway. For a ther- 

 mal element it has a xylene filled copper coil, 

 which actuates a stylus through a Bourdon 

 tube. The presure element is a copper aneriod 

 capsule which moves a coated glass slide at right 

 angle to the motion of the stylus. A double 

 analog record is thus obtained as the BT is low- 

 ered and recovered. (5) 



bathythermograph (BT) grid — A transparent 

 glass slide, marked with calibration lines of tem- 

 perature and depth, which, when superimposed 

 against a bathythermograph slide, makes it 

 possible to read off observed values of tempera- 

 ture and depth. Each instrument has its own 

 grid. (5) 



bathythermograph (BT) print — An enlarged 

 photographic print of a bathythermograph 

 slide superimposed against the appropriate 

 bathythermograph grid, annotated with par- 

 ticulars of location and data. (5) 



bathythermograph (BT) slide — A 1-inch by 1%- 

 inch glass slide with a coated (now usually gold 

 anodised, formerly smoked) surface on one side. 

 A stylus on the bathythermograph scratches 

 a depth versus temperature trace on the coated 

 surface. 



bathythermograph (BT) viewer — A small mag- 

 nifying device used in reading temperature and 

 depth values from a bathythermograph slide 

 overlaid by a bathythermograph grid. 



bathythermograph (BT) winch — A small elec- 

 tric winch primarily used for lowering and rais- 

 ing a bathythermograph. This winch is a 

 high-speed type holding about 2,500 feet of 

 %2"iiich diameter stainless steel wire. 



bay — 1. A recess in the shore or an inlet of a sea 

 between two capes or headlands; not as large 

 as a gulf but larger than a cove. (2) 



2. An inward bend in the ice edge formed 

 either by wind or current. (74) 



bay deltas — Deltas formed at the mouths of 

 streams which discharge into bays or estuaries. 

 Their advance toward the bay mouths often ex- 

 tinguishes lagoons behind bay bars or com- 

 pletely fills open bays, thus simplifying the 

 shoreline. When the delta forms at the head of 

 the bay, it is a bay-head delta. (2) 



bay-head delta — See bay deltas. 



bay ice — 1. Level ice of more than one winter's 

 growth which has remained free of hummocks 

 and is nourished by surface layers of snow. 

 (74) 



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