for study of the bottom morphology, sediments, and shallow structure of 

 western Massachusetts Bay. These data were supplemented by NOS hydro- 

 graphic smooth sheets and published scientific and technical literature. 



Massachusetts Bay is a drowned glacial terrain characterized by large 

 areas of near-level bottom interspersed with sharply irregular hills and 

 ridges. It is bordered to the west by a bold rocky coast with sections 

 of sandy beach and spits. 



Two distinctive acoustic units appear in seismic reflection profiles 

 of the study area. One is characterized by its acoustic impenetrability 

 and is believed to represent basement rock and till. The second acoustic 

 unit is characterized by relative acoustic transparency and internal re- 

 flections suggesting a stratified material. In most places the transparent 

 unit is comprised of greenish-gray silt-clay or sand deposits. 



The general contour of the acoustically impenetrable reflection unit 

 suggests a surface topography initially formed by stream erosion and later 

 disrupted by glacial erosion and till deposits. The greenish-gray silt- 

 clay deposits are confined to lows in this topography. 



Rocks and sediments underlying Massachusetts Bay range from early 

 Paleozoic to Holocene age and include extensive deposits of glacial, 

 glaciofluvial, and glaciomarine sediment. Sediment character and distri- 

 bution in the study area are complex. The chief sediment types are: (a) 

 sand ranging in size from very fine to coarse but generally in the fine to 

 medium category; (b) clean, gravelly sand and sandy gravel; (c) mixtures 

 of silt, sand, and gravel; (d) compact greenish-gray silt-clay; and (e) 

 brown, sandy clayey silt. 



Most sediments in the offshore area are judged to be relict. Active 

 deposition of modern sediments is taking place in the nearshore area and 

 fine silty sediments are accreting at a slow rate in some offshore areas. 

 However, in most places the sediments have not yet buried the relict 

 deposits. 



Six sites, scattered throughout the study area, contain sand poten- 

 tially suitable for beach restoration. An estimated total of 7.75 X 10^ 

 cubic yards of sand is distributed at the following sites: 



(a) Cat Island (1.12 X 10^ cubic yards) 



(b) Nahant (0.78 X 10^ cubic yards) 



(c) Nantasket East (0.68 X 10^ cubic yards) 



(d) Nantasket Center (0.42 X 10^ cubic yards) 



(e) Nantasket West (1.95 X 10^ cubic yards) 



(f) New Inlet (2.8 X 10^ cubic yards) 



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