BASEMENT ROCK 



RIVER MOUTH BAR 



SWASH CHANNEL 



OFFSHORE BAR 



BARS 



mmAA^^:::\:::.;:::;-y-::^::-^^^^ 



\ 



BARRIER BEACH 



(BEBi TII-4. 1934) 



|ia, Tt^. I«34) 



20 miles long, 

 wide. (2) 



250 feet thick, and 5 miles 



barnacle^One of an order (Cirripedia) of crus- 

 taceans which are enclosed in a calcareous shell 

 and sessile during their adult life. They are 

 of two general types, the acorn barnacles and 

 the stalked barnacles. Barnacles are one of 

 the most notable groups of fouling organisms. 



baroclinity — The state of stratification in a fluid 

 in which surfaces of constant pressure (isobaric) 

 intersect surfaces of constant density (isosteric) . 

 The number, per unit area, of isobaric-isosteric 

 solenoids intersecting a given surface is a meas- 

 ure of the baroclinity. (5) 



barometer — An instrument for measuring atmos- 

 pheric pressure. (35) 



barometric pressure — See atmospheric pres- 

 sure. 



barotrauma — See squeeze. 



barotropy — The state of a fluid in which surfaces 

 of constant density (or temperature) are coin- 

 cident with surfaces of constant pressure; it is 

 the state of zero baroclinity. (5) 



bar port — A harbor that can be entered only when 

 the tide rises sufficiently to permit passage of 

 ships over a bar. (73) 



barred basin — See silled basin. 



barrier — 1. In polar terminology, an early term 

 for ice shelf ; first used by Sir James Clark Ross 

 for the face of the antarctic ice shelf named for 

 him, "Ross Barrier." (5) 



2. Barrier is being replaced by ice shelf and 

 ice front in publications and maps. (59) 



barrier bar — See bar. 



barrier basin — A basin produced by natural dam- 

 ming by glacial moraines, landslides, etc. (2) 



barrier beach — (also called offshore barrier). A 

 bar essentially parallel to the shore, the crest 

 of which is above high water. (61) 



barrier berg — See tabular iceberg. 



barrier chain — A series of barrier islands, bar- 

 rier spits, and barrier beaches which extends 

 along a considerable length of coast. (2) 



barrier ice — (or shelf ice). See ice shelf. 



barrier iceberg — (or barrier berg). 1. See tab- 

 ular iceberg. 



2. A large tabular iceberg broken ofi' an ice 

 shelf. (59) 



barrier lagoon — A bay roughly parallel to the 

 coast and separated from the open ocean by bar- 

 rier islands. Also the body of water encircled 

 by coral islands and reefs, m which case it may 

 be called an atoll lagoon. (See figure for 

 atoll.) 



barrier reef — A coral reef parallel to and sep- 

 arated from the coast by a lagoon that is too 

 deep for coral growth. Generally, barrier reefs 

 follow the coasts for long distances and are cut 

 through at irregular intervals by channels or 

 passes. (2) 



barysphere — See centrosphere. 



basalt — A basic igneous (extrusive) rock com- 

 posed primarily of calcic plagioclase, pyroxene, 

 and with or without olivine. Also an inner 

 layer of worldwide extent underlying the oceans 

 and the granitic continents. (2) 



base line — 1. A surveyed line established with 

 more than usual care, to which surveys are re- 

 ferred for coordination and correlation. This 

 established line becomes the base for the com- 

 putation of the other two sides of a triangle (in 

 triangulation). (37) 



2. The line between the master and slave sta- 

 tions in Loran or other hyperbolic navigation 

 systems. 



basement — (also called basement complex, base- 

 ment rock) . An igneous or metamorphic rock 

 complex underlying sedimentary or volcanic 

 rocks. 



basement complex — See basement. 



basement rock — See basement. 



17 



