CONTINENT 



stancy of Eelative Proportions contains the 

 following constituents : 



A. Maior constituents 



Chlorine 18.980 g/kg (%) 



Sodium 10.561 



Magnesium 1.272 



Sulfur 0.884 



Calcium 0.40 



Potassium 0.380 



Bromine 0.065 



Carbon 0.028 



Strontium 0.013 



Boron 0.005 



B. Minor constituents 



Silicon 4XlO-no2XlO-» 



Fluorine 1.4X10-' 



Nitrogen 7X10"' to 6X10-' 



Aluminum 5X10 ' 



Rubidium 2X10-' 



Lithium 1X10"' 



Phosphorus 1X10"' to IXlO"' 



Barium 5X10-8 



Iodine 5X10-» 



Arsenic 2X10-no 2XlO-» 



Manganese lXlO-« to lX10-» 



Copper lX10-» 



Zinc_ 5X10-' 



Lead 4X10-' 



Selenium 4X10-» 



Cesium 2Xl0-» 



Uranium 1.5Xl0-» 



Molybdenum SXlO-i" 



Thorium 5XlO-i» 



Cerium 4X10-i» 



Silver SXlO-i" 



Vanadium 3X10-'" 



Lanthanum SXIO-'" 



Yttrium 3X10-1" 



Nickel 1X10-1" 



Scandium 4X10-" 



Mercury 3X10-" 



Gold 6X10-12 



Radium 3X10-16 to 2X 10-" 



Cadmium Trace 



Cobalt Trace 



Tin Trace 



continent — A large landmass rising abruptly 

 from the deep ocean floor, including marginal 

 regions that are shallowly submerged. Con- 

 tinents constitute about one- third of the earth's 

 surface. (2) 



continental air — A type of air whose character- 

 istics are developed over a large land area and 

 which, therefore, has the basic continental char- 

 acteristic of relatively low moisture content. 



(5) 



continental apron — 8ee continental rise. 



continental borderland — (or borderland) . A re- 

 gion adjacent to a continent, normally occupied 

 by or bordering a continental shelf, that is 

 highly irregular with depths well in excess of 

 those typical of a continental shelf. (62) 



continental drift — The concept that the conti- 

 nents can drift on the surface of the earth be- 

 cause of the weakness of the suboceanic crust, 

 such as ice can drift through water. (2) 



continental glacier — (also called continental ice). 

 A continuous sheet of land ice which covers a 

 very large area and moves outward in many di- 



rections. This type of ice mass is so thick as to 

 mask the land surface contours, in contrast to 

 the smaller and thinner highland ice. The con- 

 tinental glacier of Greenland often is called 

 inland ice, that of Antarctica, the ice cap. 



Perhaps this term is best used to describe 

 the great ice masses which characterized the ice 

 ages. (5) 



continental ice — See continental glacier. 



continental margin — A zone separating the emer- 

 gent continents from the deep sea bottom ; gen- 

 erally consists of the continental shelf, slope, 

 and rise. (2) 



continental plateau — A large elevated mass of 

 the lithosphere coinciding approximately with 

 a continent and including its continental shelf. 

 (48) 



continental platform — See continental shelf. 



continental rise — A gentle slope with a generally 

 smooth surface, rising toward the foot of the 

 continental slope. (62) 



continental shelf-r-(also called continental 'plat- 

 form) . A zone adjacent to a continent or around 

 an island, and extending from the low water 

 line to the depth at which there is usually a 

 marked increase of slope to greater depth. ( 62) 



continental slope — 1. A declivity seaward from a 

 shelf edge into greater depth. (62) 

 2. /See bathyal. 



continental terrace — This term is no longer rec- 

 ommended by the ACUF for a zone around the 

 continents, extending from low water line to 

 the base of the continental slope. It includes 

 both continental shelf and continental slope. 



continuity — The property of a field, such that 

 neighboring values of a parameter differ only 

 by an arbitrarily small amount if they are 

 close enough in space and/or time. (5) 



continuity equation — See equation of conti- 

 nuity. 



contour — A line on a chart representing points 

 of equal value with relation to a datum. It is 

 called an isobath when connecting points of 

 equal depth below sea level. See isopleth. 



contour interval — The difference in value be- 

 tween two adjacent contours. 



contra solem — See cum sole. 



contrast — In optics, the ratio of the target reflec- 

 tance {TB) minus the background reflectance 

 {BR) to the background reflectance, that is, 



TR-BR 

 BR ' 



expressed as percentage. 

 convection — In general, mass motions within a 

 fluid resulting in transport and mixing of the 

 properties of that fluid. Convection, along with 

 conduction and radiation, is a principal means 

 of energy transfer. 



Distinction is made between : free convection 

 (or gravitational convection), motion caused 



38 



