probably shallow water deposits similar to marsh or mudflat deposits that were laid 

 down during the transgressive phase of the submergence. 



Bloom (1959), working in southwestern Moine, applied the name Presumpscot For- 

 mation to the late glacial marine clays of southern Maine. In the southwestern part of 

 the state, the clays are gray to blue-gray, thick to thin bedded, silty clays separated 

 by thin laminae of silt or fine sand. True varves are not found, but rhythmic bedding 

 is common. In some locations, boulders, apparently ice-rafted, are found imbedded 

 in the clays. Bloom believes these clays to be "glacial rock flour." The clays are 

 sandier than those found in the Penobscot Bay region. 



IV. SURVEY OBSERVATIONS 



A. Oceanographic Observations 



During the survey period August to October 1959, observations of temperature, 

 salinity, and currents were made in the bay and its approaches. The saline wedge 

 was only weakly developed during this period, but a gradual headward movement 

 of the saline bottom water and a net seaward flow of the fresher surface water were 

 observed. In the southern part of the survey area, current observations showed on 

 ebb and flood of the bottom water with the flood predominating. The maximum observ- 

 ed flood velocity of the bottom water was 0.7 knot off Rockland. The average was 

 considerably less. Farther north there was a very weak flood, and in the northern 

 extremity of the bay, bottom currents were below the threshold of the current meter. 



Current observations in the upper layer of water showed a flood and an ebb at 

 nearly all locations with the ebb predominating. The currents were weaker in the 

 north but reached a maximum ebb of 1 .0 knot off Rockland. 



In other seasons of the year, during periods of greater river discharge, current 

 speeds greater than those observed during the survey period can be expected. Dur- 

 ing periods of peak discharge for the Penobscot River, April and May, the river flow 

 is many times greater than during August and September (U.S.G.S. Water Supply 

 Paper, 1947). 



The tidal range in the Bay is large. The mean range exceeds 9 feet in the south 

 and 10 feet In the north . 



During the survey period second swell conditions in the area were very moderate. 

 During the winter months, however, sea states can become severe, especially, in the 

 unprotected approaches to the bay. At these times, wave action probably extends to 

 the bottom in a large portion of the approaches to the bay and in the southern portion 

 of the bay proper . 



