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108 OCEANOGRAPHY IN THE NEXT DECADE 



instrument systems will probably increase, especially with newly 

 developed sensors, such as complete meteorological and wave 

 measurements and underwater sensors capable of measuring bio- 

 logically, chemically, and geologically relevant variables. Such 

 comprehensive packages already exist or are under development, 

 but their use will become more routine as the decade progresses. 

 The need to study small-scale dynamic features, such as fronts on 

 the continental shelf and wind-forced mixing in estuaries, will 

 create a greater dernand for towed devices that can sample rapidly 

 and repeatedly in three dimensions. These too are becoming available 

 but will be used more frequently in the future. Similarly, there 

 will probably be a need for new sediment samplers that can also 

 measure near-bottom currents and sedimentary conditions. Ad- 

 vances in remote sensing of coastal areas will benefit the field. 



Introduction 



The coastal ocean lies at the junction between land and the 

 open ocean and includes estuaries and embayments. By virtue of 

 its location, it is a setting of unusual societal importance. Most 

 of the world's population centers are located near the ocean, so 

 that pollution, recreation, and shipping impact the coastal envi- 

 ronment and are likewise affected by coastal processes. As the 

 U.S. population continues to shift toward the ocean, these consid- 

 erations will become increasingly important. Economically, the 

 coastal ocean is also of great importance, for example, in terms of 

 mineral (especially petroleum) exploitation, recreation, and fish- 

 eries. The conflicts among uses of the coastal region have height- 

 ened the public's awareness of the region — and of the need to 

 study it in detail. 



The coastal region is defined here as the portions of ocean and 

 atmosphere extending seaward from the surf zone and the heads 

 of tidal estuaries and overlaying the continental shelf, slope, and 

 rise. Geologically, this region of the continental margin forms 

 the transition between the thick continental crust and the thin- 

 ner oceanic crust, both of which float on the underlying mantle. 

 The continental shelf is essentially the submerged edge of the 

 continental crust. Broadly speaking, continental margins are of 

 two types (Figure 3-3). Those on the leading edges of crustal plate 

 motions (often near trenches) tend to be characterized by narrow 

 shelves, (e.g., the West Coast of the United States). Margins on 

 the trailing, relatively inactive edges of continents tend to be 

 characterized by broad, relatively flat shelves (e.g., the U.S. East 



