70 Coastal Processes (Posters)

Tuesday, 21 March 2017
1:30 PM - 5:30 PM
Urban, 17th Floor

STRATIGRAPHIC INVESTIGATION OF SELECT NEW ENGLAND SALT MARSHES AND THE POTENTIAL OF PAST HIGH ENERGY EVENTS BASED ON SEDIMENT LITHOLOGY

Paper number: 70-6
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Salt marshes in New England are known to preserve records of coastal conditions over the Late Holocene Epoch. The marshes can preserve siliciclastic layers of past high energy events such as tsunamis, Nor’easters and hurricanes. The purpose of this study is to investigate the stratigraphy of select salt marshes along the coast of New England, including Massachusetts and Maine, in an attempt to find evidence of past high energy events that deposit coarse grained sediments. In this study we extracted several cores from Scituate MA, (core length = 200 cm), Essex MA, (core length = 290 cm), and Saco ME, (core length = 159 cm and 164 cm). All cores were extracted using a square rod Livingstone piston corer and transported to the lab and stored at 4°C. At the lab cores were split lengthwise, imaged, and described lithologically. All cores presented similar stratigraphy listed here from top down, 1) a fibrous peat with significant vegetation and roots, 2) a silt layer with minor fine grained sand particles with a lack of peat and vegetation, 3) a mud layer with consistent decrease of vegetation and organic matter, 4) a massive glaciomarine clay where the Livingstone corer was unable to fully penetrate. The two cores extracted in Saco, ME had a preserved coarse sand layer (0.5 – 1.0 mm) in the stratigraphic column. Location one at Saco was extracted 45 meters from the shore line and presented the sandy layer 88 cm below the surface in stratigraphic layer 2. The second location was extracted 762 meters from the shore line and presented a sand layer (1.0 – 2.0 mm) 48 cm below the surface at the base of stratigraphic layer 3. This second sand layer is interpreted as being unconformably above the glaciomarine clay, and likely represents a transgressive sand unit. The sand bed found at Saco location 1 may be associated with sand beds found in the region that have previously been interpreted as tsunami deposits, dated between approximately 2000-2300 B.P (Tuttle, 2005). This bed is similar to previous deposits in that it contains a coarse-grained sandy bed between 60 and 150 cm below the surface and between 50-500 meters from the shore line (Tuttle, 2004). Pending radiocarbon dates will constrain the age of this new sand bed.

Geological Society of America Abstracts with Programs. Vol. 49, No. 2

doi: 10.1130/abs/2017NE-290784

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