All symbols used in the present work are defined at the appropriate place in the text, which can be found by reference to the index at the end of the volume. The units defined below, and the symbols by which they are identified, are confined to a general list of those most commonly used in the present work; other units will be defined where necessary in the text itself. It must be noted that a number of traditional units have been retained as a matter of policy throughout the work because they are still widely used in the current as well as in the past literature; e.g. the litre has been used as a unit volume although IAPSO have recommended that for high-precision measurements of volume it be replaced by the cubic decimetre (dm3). For a detailed treatment of the use of SI units in oceanography see the IAPSO recommendations published by Unesco (1985). <...>

The fundamental question underlying marine geochemistry is, ‘How do the oceans work as a chemical system?’ At present, that question cannot be answered fully. The past four decades or so, however, have seen a number of ‘quantum leaps’ in our understanding of some aspects of marine geochemistry. Three principal factors have made these leaps possible:
1    advances in sampling and analytical techniques;
2    the development of theoretical concepts;
3    the setting up of large-scale international oceanographic programmes (e.g. DSDP, MANOP, HEBBTE, GEOSECS, TTO, VERTEX, JGOFS, SEAREX, WOCE), which have extended the marine geochemistry database to a global ocean scale. <...>

Basic data on the opening of backarc basin, South China Sea (abbreviated as SCS hereafter) basin, were obtained through a two-year Japan and China cooperative joint marine geophysical survey in 1993 and 1994. Some new gravity, magnetic and seismic structural data by reflection as well as refraction study of SCS were obtained and added to existing data. A systematic three component magnetic measurement was made for the first time in this basin. These data in addition to those of earlier studies are constraints for depicting a thinning of a continental crust and later followed by a backarc basin opening by ocean floor spreading. Gravimetric and magnetic anomalies, heat flow, and ages of drilled rocks from this area are referred to speculating on the opening scheme of SCS. Origin of disoriented and scattered magnetic anomaly lineations is suggested to be due to intermittent activities along opening ridge systems of SCS. <...>

Exploration of the oceans using the techniques of the geophysicist has had a profound influence on our understanding of the Earth and its behaviour through time. Observations in the deep ocean have played a key role in establishing modern plate tectonic theory, transforming Earth Science in ways that were quite unexpected when the first geophysicists put to sea. Measurements in shallower waters have revealed how continental margins form, subside and become covered with sedimentary accumulations.