to 6.4 m in Eastport (NOS, 1987a). Tidal current velocities are 

 variable, depending on local bathymetry, but are typically 0.5 

 knot (0.25 m/sec) in the open nearshore off the central Maine 

 coast, increasing to more than 2 or 3 knots (1-1.5 m/sec) in 

 embayments (NOS, 1987b) . Runoff in rivers is concentrated in two 

 peaks, a primary spring event and secondary fall event. 



Maine's rivers are generally low in turbidity, except during 

 the spring maximum. Extreme events, such as the greater than 100 

 year flood of April 1, 1987 (Hasbrouck, 1987) can bring 

 considerable sediment to the nearshore. Peak flows from the 

 combined Androscoggin and Kennebec Rivers at that time were 9,118 

 m-^/sec, as compared to normal flow of 331 m 3 /sec, 27.5 times as 

 great. Goldschmidt and Stumpf (1988) have shown, in satellite 

 photos from April 2, 1987, an extensive sediment plume extending 

 from the mouth of the Kennebec trending southwest over the west- 

 central Maine coast, with peak turbidities as high as 30-100 

 mg/1 . 



Sediment supply to and from the coastal zone has been a 

 subject of some discussion. Limited oceanographic data by Graham 

 (1970) suggests an alongshore net southwesterly shelf drift, 

 while Schnitker (1972) called for offshore sources of mud to the 

 Montsweag Bay part of the Sheepscot estuary. McAlice and Jaeger 

 (198 3) used current meter and salinity measurements to show the 

 variation from well mixed to partially stratified conditions in 

 the Sheepscot River estuary. FitzGerald and Fink (1987) found 

 similar conditions in the Kennebec River mouth, indicating well- 

 stratified estuarine circulation only in spring. Farrell (1970) , 

 however, indicated that the Saco River is stratified at all 

 stages of flow. Belknap et al. (1986) , Kelley (1987) and Shipp 

 et al. (1987) suggest that sediment is recycled within the 

 estuaries during transgression, that offshore sources are not 

 reguired, and that in fact some fraction must be lost offshore. 

 Hay (1988) has completed a sediment budget for Casco Bay 

 demonstrating a large net loss to the offshore during the 

 Holocene transgression. 



To our knowledge, no other submersible-based observations of 

 sedimentology have been made in Maine prior to this study. 

 Considerable work has been done in southern New England (e.g. 

 Valentine et al., 1980; Ryan et al., 1978). Limited grab 

 sampling associated with seismic profiles has been published 



(Folger et al., 1975; Ostericher, 1965), but the present Minerals 

 Management Service project by the Maine Geological Survey (Kelley 

 et al., 1987a, b) is the most comprehensive data set available. 

 Cores have been collected in the estuaries (Belknap et al . , 1986; 

 Hay, 1988) , but only limited core data is available offshore 



(Kelley et al., 1986; Schnitker, 1974). 



METHODS 



The approach to this study was to use existing seismic 

 reflection, side-scan and sample data to compare with submersible 



149 



