the information collected in the conduct of the research program toward 

 the CERC mission, especially in terms of Continental Shelf structure 

 (Meisburger and Duane, 1969), Continental Shelf Sedimentation (Field, 

 Meisburger and Duane, 1971), and its potential application to histori- 

 cal geology and engineering studies of the shelf, the sand inventory 

 program is now referred to as the Inner Continental Shelf Sediment and 

 Structure Program (ICONS). 



2. Field and Laboratory Procedures 



The exploration phase of the ICONS program uses seismic reflection 

 profiling supplemented by cores of the marine bottom. Additional sup- 

 porting data for the studies are obtained from USC^GS hydrographic boat 

 sheets and related published literature. Planning, and seismic-reflec- 

 tion profiling, coring, positioning, and analysis of sediment obtained 

 in the cores are detailed in Geomorphotogy and Sediment Charaateristies 

 of the Nearshore Continental Shelf ^ Miami to Palm Beach ^ Florida (Duane 

 and Meisburger, 1969) . However, a brief description of techniques is 

 germane to this paper and follows. 



a. Planning - Survey tracklines were laid out by the CERC Geology 

 Branch staff in either of two line patterns: grid and reconnaissance 

 lines. A grid pattern (line spacing about 1 statute mile) was used to 

 cover areas where a more detailed development of bottom and subbottom 

 conditions was desired. Reconnaissance lines are one or several con- 

 tinuous zigzag lines followed to explore areas between grids, and to 

 provide a means of correlating sonic reflection horizons between grids. 

 Reconnaissance lines provide sufficient information to show the general 

 morphologic and geologic aspect of the area covered, and to identify 

 the best places for additional data collection. 



Selection of core sites was based on a continuing review of the 

 seismic profiles as they became available during the survey. This 

 procedure allowed core-site selection based on the best information - 

 available; it also permitted the contractor to complete coring in one 

 area before moving his base to the next area. 



b. Seismic Reflection Profiling is a technique in wide use for 

 delineating subbottom structures and bedding planes in sea floor sedi- 

 ments and rocks. Continuous reflections are obtained by generating 

 repetitive high-energy, sound pulses near the water surface and record- 

 ing "echoes" reflected from the bottom-water interface, and subbottom 

 interfaces between acoustically dissimilar materials. In general, the 

 compositional and physical properties which commonly differentiate sedi- 

 ments and rocks also produce acoustic contrasts. Thus, an acoustic 

 profile is roughly comparable to a geologic cross section. 



Seismic-reflection surveys of marine areas are made by towing 

 sound-generating sources and receiving instruments behind a survey 

 vessel which follows predetermined survey tracklines. For continuous 



