like an automobile spark plug. The energy is created as an electrical spark 

 which sends sonic waves through the water to the bottom and subbottom. 

 These waves are refracted and reflected, and return to the surface where 

 detection is accomplished by a string of hydrophones. In this manner a 

 vertical profile of the water column, the surface of the shelf, and strati- 

 fication beneath the bottom is derived. Originally a single low-powered 

 energy source was used and the record extended from water surface to a 

 depth of about 350 feet. At present two energy sources (one low and one 

 medium) are used and recorded on the same paper. The low-enerpy portion 

 of the record extends from water surface to a depth of about 150 feet ; 

 resolution is about two feet. The medium-energy portion extends from the 

 surface to a depth of about 450 feet; resolution is much less than that 

 from the low-energy signal. This, however, does permit investigation of 

 the deeper stratification and this makes the entire program more attractive 

 scientifically. 



The second exploration tool is known as the "Vibracorer . " It is a 

 self-supporting, compressed-air-powered coring tool. While the initial 

 penetration capacity was 12 feet, the present capacity is 16 feet. The 

 core is contained in a transparent plastic tube which is approximately 

 three inches in inside diameter. Inasmuch as the tool is free-standing, 

 it is unnecessary to hold the survey boat with more than a single anchor 

 and thus the time required to obtain a core is drastically reduced. The 

 entire operation has never taken more than 15 minutes, after arrival at the 

 core site. Usually the core is sampled at one-foot intervals except when 

 obvious stratification exists. Size distribution analysis of each sample 

 is necessary to determine the suitability of the sediment for beach purposes 

 and to identify those strata which have been detected by the geophysics. 



Upon combining the geophysics and data from the cores, it is possible 

 to map areas of suitable sand deposits in three dimensions. With these 

 maps it is possible to derive quantitative data on the volume of material 

 available. 



It was mentioned earlier that the work started in June 1964 at four 

 selected areas off New Jersey. The areas are in the vicinity of Sandy Hook, 

 Barnegat Inlet, Little Egg Inlet, and Cape May, At each area a rectangular 

 grid was aid out, the spacing between exploration lines was one statute mile. 

 Inspection of the geophysical records and knowledge of the geology and the 

 shore processes were the basis for determining the location of core sites. 

 By the end of October 1964 the contractor had completed all of the work, 

 some 1,500 miles of exploration lines and approximately 200 borings, 



A similar increment of work is presently nearing completion. Operations 

 started on January 6, 1965 in the vicinity of Cape Florida and have progressed 

 to Cape Kennedy, the northern limit of the area. Over 100 cores and 1,000 

 miles of exploration lines have been completed at this time. It is most in- 

 teresting to note that Cape Kennedy and the shoals adjacent thereto appear 

 to be controlled by structure. The geophysical records show a broad, roughly 

 north-south arching at depths of about 3 to 400 feet below Vviater surface. 



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