SUBMERGED ENVIRONMENTS OF SACO BAY, MAINE

Rapid relative sea-level change was the primary process forcing alteration in littoral environments in Saco Bay, Maine over the last 14,000 years. Bedrock geology, glacial deposits and postglacial deposits have constrained the morphology of Saco Bay through the last regression, with a lowstand at about 60 m below present sea level at approximately 10,500 years ago, and the subsequent transgression. To understand the environmental conditions present at the lowstand of sea level in Saco Bay, ME, we gathered multibeam bathymetric and sidescan backscatter data in August 2003 and coupled it with previously collected seismic reflection profiles and bottom samples. The new observations were collected in a narrow swath of data in 40 to 80 m water depth targeting presumed lowstand deposits. The pairing of bathymetric and surficial geology with stratigraphy has allowed the interpretation of ancient, submerged beach, river and tidal environments, which have undergone continued modification by modern processes. Placing these environments into a sequence stratigraphic framework and series of paleo-geographic reconstructions have aided in our knowledge of the evolution of the bay and locations of sand deposits. The reconstructions and framework will serve as a basis for future seismic and coring work planned for 2004. In this investigation of the influence of relative sea-level change on past environments in a sandy embayment, we seek to further the understanding role of isostasy in past depositional environments and subsequent modifications. This understanding of past sea-level change will also provide insight to the modern environment’s response to a changing sea level and consequent environmental stress.