(1938) examined sediments along widely spaced 

 traverses of the entire shelf. Shepard and 

 Cohee (1936) analyzed many closely spaced 

 samples off New York and Connecticut. The only 

 modern study, and one that also overlaps on to 

 the continental slope, is that of Moore and Gors- 

 line (I960) on the area off southeastern United 

 States. Reconnaissance study of sediments be- 

 yond the Continental Shelf has been made by the 

 Lamont Geological Observatory and reported 

 in a series of papers culminating in a summary 

 paper by Ericson, Ewing, Wollin, and Heezen 

 (1961). Many other studies have been made of 

 sediments in estuaries and on beaches, but 

 all are on local scale and unrelated. 



Sediment will be collected as short-core or 

 grab samples (fig. 2) about 18 km apart on lines 

 about 18 km apart across the Continental Shelf. 

 Adherence to a grid will not be strict, because 

 allowance must be made for variations of sedi- 

 ment related to topographic features. At the 

 approximate spacing of one sample per 350 sq 

 km, a total of about 1,500 samples would be ob- 

 tained. Probably about 2,000 samples will be 

 obtained in order to portray more accurately 

 certain local variations. A fine start has been 

 provided by a suite of about 300 samples col- 

 lected on such a grid spacing in the Gulf of Maine; 

 these were obtained during 1959-61 by the Bu- 

 reau of Commercial Fisheries in an effort to 

 relate fish populations to sediment character- 

 istics (Wigley, 1961). Laboratory studies will 

 be made of texture carbonate, organic carbon, 

 and nitrogen contents and of mineralogy, includ- 

 ing clays and coarse fractions. These para- 

 meters are usually sufficient to determine the 

 origin of sediments. Sediments on the continental 

 slope to be investigated will be obtained by taking 

 several hundred cores with the piston corer 

 (fig. 3). These cores will allow study of the dis- 

 tribution of calcium carbonate and organic mat- 

 ter with depth, as well as changes inpore-water 

 chemistry and rates of deposition. 



The coarse grid of sediment sampling can be 

 considered good reconnaissance, and it will cer- 

 tainly allow the delineation of areas of glacial, 

 organic, authigenic, residual, relict, and modern 

 detrital sediments (Emery, 1960, p. 198-208), 

 and establish a framework for more-detailed 

 studies of the shelf, including sediments of the 

 past. 



Lithology 



Rocks cropping out on the Continental Shelf and 

 in the submarine canyons were dredged by Stet- 

 son (1949), particularly in the region between 



Massachusetts and Virginia. Little rock sam- 

 pling has been done elsewhere on the shelf. The 

 best places for dredging are, of course, the walls 

 of canyons, the shelf-break, and the face of the 

 steeper parts of the continental slope (fig. 4). 

 Stetson's work will be extended and detail added 

 with possibly 300 well-distributed dredgings 

 made from Gosnold. Additional rock samples 

 may come from cores--both incidental and inten- 

 tional. Cores have the advantage over dredgings 

 of being more precise in depth and position, but 

 the disadvantage of being less representative of 

 an area and less certain of success. Eventually, 

 some offshore drilling will be done to confirm 

 interpretations derived from outcrops and from 

 geophysical work. 



Preparation and preliminary investigation of 

 the rock samples will be undertaken at Woods 

 Hole, in addition to the sorting and identification 

 of most rock types in the predominantly igneous 

 and metamorphic pebbles and boulders of glacial 

 till and ice rafting. Final identification and cor- 

 relation of sedimentary rocks in place will be 

 made mostly or largely at the Geological Survey 

 in Washington, where the staff is familiar with the 

 lithology of the adjacent land, and where type 

 rock samples and representative fossils col- 

 lected from outcrops during many years are 

 available. Also, the Geological Survey is making 

 a compilation of Coastal Plain subsurface strat- 

 igraphy. 



The identification and study of rock specimens 

 obtained from the sea floor may provide new in- 

 formation on the continuity or facies changes of 

 strata well known in outcrop on land. Strata 

 cropping out on land, particularly the Tertiary 

 strata, consist largely of nonmarine sediments, 

 but probably these grade seaward into their ma- 

 rine equivalents. 



Structure 



Many refraction and reflection seismic lines 

 have been run across the Continental Shelf by 

 Ewing and associates at Lamont Geological Ob- 

 servatory (a representative report is one by 

 Drake, Ewing, and Sutton, 1959). Some have been 

 carried farther seaward by the same group and 

 by Hersey, Bunce, Wyrick, and Dietz (1959) of 

 the Woods Hole Oceanographic Institution. 



Other kinds of geophysical data are needed 

 more urgently at present. Chief of these are 

 continuous reflection seismic profiles (fig. 5) 

 of the type obtained by sparker and thumper. 

 Such seismic profiling is planned for Gosnold to 

 be done mostly at night. The records should 

 reveal the thickness and distribution ofpostgla- 



