Surficial Geology: 



The surficial geology of Region 4 is similar to that of Region 3 

 dominated by thin tills on bedrock highs with valley infillings of marine sedi- 

 ments. Because the terrain is dominated by granitic intrusives which underly 

 the resistant topographic highs, the tills tend to be bouldery and of coarser 

 texture than the tills further to the southwest (Thompson 1978) . 



End moraines are not as prevalent in number over the terrain in Region 4 , 

 but these features also tend to be coarser than their southern counterparts and 

 also tend to contain a high percentage of boulder particles. 



Ice-contact deposits (kames, eskers, and small deltas) are local, but a 

 large concentration of these deposits occurs in Belfast, Searsport and Stockton 

 Springs . 



The soils of Region 4 are loamy and clay soils. Peru, Lyman, and Scantic 

 soils are common on the mainland on low elevation surfaces, while poorly devel- 

 oped organic soils and bare ledge are common on the outer islands and higher 

 coastal mountains. 



Marine Geology: 



The Penobscot River estuary, the largest fine-grained estuary along the 

 Maine coast dominates the marine and estuarine environments of this area. The 

 Bagaduce River estuary is the only other sizeable estuary within the region, 

 which, because of its strong topographic and bathymetric relief, is dominated 

 by subtidal marine systems of shallow wave-dominated platforms and deeper 

 tidal-current dominated channels. 



Intertidal areas not associated with the estuarine systems are a part of 

 wave-dominated or tide-dominated embayment systems. These systems are composed 

 primarily of subtidal and intertidal sand and mud flats, aquatic beds, tidal 

 channels and ledge environments . 



The sediments of the lower Penobscot estuary have been studied by 

 Ostericher (1965), Hathaway (1972). and Folger (1972 a & b) . Folger (1972 a) 

 characterizes the basin as one of high tidal range and relatively small 

 sediment input coupled with high current velocities throughout most of the 

 estuary ( > 100 cm/ sec) and vigorous wave action. The resultant of these 

 conditions is a sediment distribution which coarsens from the basin channel 

 laterally to the upland margins and down estuary. Clays occur throughout 

 the deeper portions of the upper lower estuary and coarsens to silt between 

 Rockland and Vinalhaven. Medium to fine sand covers the bay bottom south of 

 Rockland. Coarse sand and gravels exist close to the shoreline and at the 

 mouths of small bays off Penobscot Bay. 



Cores penetrating surface sediments indicate that in the upper regions of 

 the lower Bay, clay grades down to sand; in the mid-portions, clay predomin- 

 ates from the surface to at least depths of three meters; silt or fine sands 

 to fine silts at depths in the lower Bay (Ostericher 1965). 



(Continued) 

 2-D-6 



