Vinalhaven Island are the largest. These islands divide the bay into East 

 Penobscot Bay and West Penobscot Bay . 



B. Bathymetry 



The bathymetry of the bay and its approaches, shown in Figure 1, was taken 

 from Coast and Geodetic Survey (C& GS) charts 310, 311, 313, and 322 and is 

 plotted on a base taken from C&t GS chart 1203 . The bottom of the bay is very 

 irregular with many isolated highs and depressions. South of the latitude of Rockland, 

 the bay deepens rapidly to a maximum of about 540 feet and shoals to 250 feet 5 miles 

 farther south . A possible continuation of this basin may be the channel curving to 

 the southeast as suggested by the contours. The topography in the approaches to 

 Penobscot Bay is also very irregular , but depths gradually increase toward the Gulf 

 of Maine where the bottom topography is similarly very irregular (Murray, 1947). 



C. Geologic Setting and Previous Work in the Area 



The shores and islands of Penobscot Bay consist of argillaceous metasediments, 

 limestone, quartzlte, and intrusive and extrusive acid and basic igneous rocks, all 

 of Early and Middle Paleozoic age (Bastin, 1908). These rocks usually are exposed 

 along the shores of the bay and its approaches and are only thinly covered with 

 glacial and postglacial deposits elsewhere in the region. 



Relatively little is known of the glacial and postglacial history of Maine. 

 Problems that have not as yet been resolved include: the southern limit of glaciation, 

 the number of glaciatlons, the duration of glaciation, and the number and extent of 

 sea level changes during late glacial and postglacial time. 



It is believed that there were at least two major glacial advances over Maine 

 during the Pleistocene. The glaciation apparently did not result in a drastic alter- 

 ation of the original topography (Johnson, 1925). The soil end weathered bedrock 

 were removed, but large scale ice erosional features are generally lacking. 



The evidence for the two glacial advances rests primarily on two sequences of 

 marine sediments, one preceding and one following esker formation. The sequence 

 of deposits from the youngest to the oldest is as follows: (Leavitt and Perkins, 1935) 



Marine sediment . 



Drift, including eskers . Ice flow south . 



Marine sediments. Sediments deformed as though by bergs. 



Drift, including eskers. Ice flow southeast. 



Flint (1953) suggests that the older drift is part of the lowan-Tazewell Complex and 

 that the younger drift represents the Cory substage of the Wisconsin glaciation. The 



