Based on the assumption that available data are representative, the area 

 as a whole contains relatively small amounts of suitable material. 



Potential sand sources are scanty in level bottom areas. Although 

 sand is the common surface deposit in these areas, it is generally fine 

 to very fine grained and unsuitable for beach fill. Furthermore, the thin 

 and discontinuous sand cover is almost everywhere underlain by the ubiq- 

 uitous green- gray silt and clay. Some of the smooth surface mounds which 

 occur in places in level bottom areas contain thicker deposits of sand. 

 Although little information is presently available on these features, 

 they are judged to be the best prospects in level bottom areas for future 

 exploration. 



Sand potential of the submarine hills and ridges is poor in recovery 

 of adequate material from these features because of their bedrock or till 

 composition. Marine reworking and selective sorting of the till compos- 

 ing or mantling submarine hills and ridges during transgressive-regressive 

 phases of the Holocene produced some usable deposits adjacent to the 

 source features (Willett, et al . , 1972). Similarily, present-day coastal 

 erosion of drumlins and other till features has provided sand for beaches 

 and spits along the coast of the study area. 



Jn channels between inshore hills and ridges, current and wave action 

 are locally forming modern deposits of sand. A deposit in Cat Island 

 Channel north of the main grid area (see Section V, 2b) is an example of 

 a modern tidal-channel deposit containing suitable bottom material. Since 

 little data have been collected on the inshore hill and ridge areas because 

 of navigation difficulties in such places, their potential as sand sources 

 cannot be assessed. Future exploration of the more accessible channels 

 may prove worthwhile, especially those in which tidal currents are compe- 

 tent to carry sand-size material. 



b. Potential Offshore Borrow Sites . Specific sand deposits potent- 

 ially usable as offshore borrow sites are discussed below and summarized in 

 Table 4. Since information on these ICONS sites is sparse, detailed 

 surveys are considered necessary before a site is selected as a project 

 borrow zone. The prime project NOMES site is. also discussed and potent- 

 ially usable sand and gravel deposits within study limits reported by the 

 MCMI are plotted in Figure 14. Details on the latter sites are given in 

 Willett, et al. (1972) and Setlow (1973). 



(1) Cat Island Channel . The Cat Island Channel sand deposit is 

 centered at 42°30.2'N., 70°48.9'W. off Cat Island in the northern recon- 

 naissance area (Fig. 15). The deposit lies in 30 to 55 feet (9.1 to 16.7 

 meters) of water, is roughly rectangular in shape, measures approximately 

 330 by 850 yards, and covers an area of about 280,000 square yards. Core 

 data indicate that the deposit is at least 12 feet (3.7 meters) thick. 

 Seismic reflections and topographic data suggest that it may be 20 feet 

 (6.1 meters) thick (Figs. 15 and 16). 



44 



