INTRODUCTION 



In most atlases the oceans are shown as 

 monotonously uniform expanses, but con- 

 trary to such indications they are far from 

 simple. Not shown on ordinary charts are 

 the mountain ranges and canyons on the 

 floor of the ocean. These hidden features 

 of the earth's solid surface contain records 

 of its past as important as any that have 

 been deciphered from exposed rocks. In 

 the deep ocean far from shore, sediments 

 are deposited with extreme slowness, so 

 that a thickness of a few feet may reveal 

 the earth's history over a long period. Near 

 shore, sediments are being deposited today 

 in the same manner as were the sediments 

 of past geologic ages which are now ex- 

 posed on the continents. Study of marine 

 sediments therefore yields many clues to 

 the interpretation of the geologic record. 



The ocean and the atmosphere together 

 are an enormous heat engine which is more 

 complicated, in some ways, than any arti- 

 ficial engines that drive our factories. 

 Almost none of the engineer's theoretical 

 simplifications and approximations may be 

 applied to the physical motions of matter 

 and heat in the ocean. The huge scale of 

 the current systems and of the motions re- 

 sulting from frictional forces, as well as the 

 effects of the earth's rotation, make it very 

 difficult to use the results of hydraulic labo- 

 ratories to advance our understanding of 

 oceanic circulation. 



There are four principal kinds of move- 

 ment of ocean water, probably not entirely 

 independent of one another: (1) Surface 

 waves, generated by the winds, which 

 travel great distances, so that waves pro- 

 duced by storms in the South Pacific may 

 break on the California coast. (2) Tides, 

 caused by the gravitational action of 

 the moon and sun. (3) Surface currents, 

 such as the Gulf Stream, caused in part by 

 steady winds like the Trades, but strongly 

 influenced by the earth's rotation, as well 



as by the boundary between land and sea. 

 (4) The deep circulation maintained by 

 temperature and salinity differences, de- 

 pendent on climatic conditions over vari- 

 ous parts of the seas. 



Not only is the interaction of the atmo- 

 sphere and ocean apparent in the wind- 

 driven currents and surface waves, but con- 

 versely the ocean is the source of much of 

 the water that falls as rain. It is also an 

 enormous reservoir of heat that influences 

 climate. Consequently, meteorology and 

 oceanography are and will continue to be 

 strongly interdependent sciences. 



Sea water is a complex chemical system 

 that has greatly influenced the evolution of 

 life. It contains almost all of the chemical 

 elements, many of which take part, even in 

 extreme dilution, in biological and other 

 processes as diverse as the growth of plants 

 and the cementation of loose sand into 

 sandstone. Rainfall and evaporation of 

 water at the sea surface and the run-off 

 from the land both tend to change the 

 chemical composition of sea water locally. 

 Despite this, the relative proportions of its 

 major constituents are almost constant over 

 the whole world and at all depths. 



The ocean supports a fauna and flora at 

 least as varied as those of dry land. Plants 

 grow in the upper layers of the sea pene- 

 trated by bright sunlight. Many of them, 

 microscopic in size, float at sea in the sur- 

 face waters. Despite their small size, their 

 total photosynthetic activity is many times 

 that of all the fields and forests of the land. 

 About a thousand feet below the sea sur- 

 face, in almost every latitude and longi- 

 tude, there is another water layer in which 

 life is apparently very abundant. The 

 nature of these deep-living organisms is at 

 present only a matter for speculation. Even 

 the abyssal depths of the ocean support 

 life, as has recently been re-emphasized 

 through submarine photographs of the 



