FORAMINIFERA FROM THE PRESUMPSCOT FORMATION: EVIDENCE FOR PALEOSALINITY AND PALEOBATHYMETRY IN THE WANING PHASES OF MARINE EMERGENCE OF CENTRAL MAINE

In central and coastal Maine, the immediately postglacial record is predominantly one of marine submergence and subsequent re-emergence of the land. The timing of this re-emergence and character of the initial landscape are of particular importance and interest. A sample was taken from each of four diffusely fossiliferous pockets of shelly marine silts in an abandoned gravel pit in Norridgewock, Maine; all samples were collected from within the upper 6.5 m of the massive marine silts of the Presumpscot Formation. Small samples were taken for ostracode and foraminiferal analyses, and large bulk samples were collected for molluscan faunal study and radiocarbon age determination. Though age determinations on these samples are pending, past experience has been that comparable samples in this region yield ages of 12,300-12,500 ¹⁴C years b.p. This presents initial results of the study of the foraminiferal fauna recovered from these deposits. The dominant foram species present in the samples was Elphidium excavatum forma clavata, with Protelphidium orbiculare, Elphidium incertum, Buccella frigida, and Globulina glacialis in decreasing abundance. This assemblage indicates the following paleo-depositional environment: 22-32 ppt salinity, -1 to 15^oC temperature, and less than 30 m water depth. The foraminifera were likely deposited in a brackish marginal marine setting during the marine flooding of Maine.