Barrier beach evolution in southwestern Maine: Constraining a sediment budget by analyzing depositional products in Saco Bay

Conference · Mon Mar 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5934226

Barber, D C; Belknap, D F ^[1]; Kelley, J T ^[2]

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1. Univ. of Maine, Orono, ME (United States). Dept. of Geological Sciences
2. Maine Geological Survey, Augusta, ME (United States)

Saco Bay, in southern coastal Maine, is bordered to the northwest by a sandy barrier beach framed by bedrock headlands. Although the barrier has not migrated significantly during the late Holocene, large alongshore sediment redistributions within the system have occurred in this century. Drastic coastal erosion in some local communities has spurred research aimed at quantitatively describing the Saco Bay sediment budget. Depositional products in the nearshore regions of the bay, out to about 10 km offshore, were analyzed with 178 km of seismic reflection profiles and 29 km[sup 2] of side-scan sonographs collected in 1991--1992. Vibracores confirm seismic interpretations of a Holocene shoreface wedge underlain by glaciomarine mud. The textural boundary between sand and glaciomarine mud in nearshore cores marks the Holocene ravinement (transgressive) unconformity. Throughout the 15--60 m depth zone, glaciomarine reflectors are truncated at the seafloor. Side-scan sonar interpretations of seafloor textures were confirmed by 175 existing bottom grab samples. Large areas of rippled sand and gravel occur in depths from 10--40m. These features suggest sediment transport, but rates are not easily quantified. An isopach map created using a geographic information system shows the shoreface to be the largest sand reservoir in the Saco Bay system. The glaciomarine sediments in Saco Bay were deposited during deglaciation, at a time of higher than present local relative sea level. The Saco River delivered large volumes of sand of the area during the postglacial relative sea-level lowstand. This fluvial sediment supply has probably persisted, though at a decreasing rate, during the Holocene. The sandy barrier system in Saco Bay developed as sea level rose and the glaciomarine and fluvial deposits were reworked and transported.

• OSTI ID: 5934226
• Report Number(s): CONF-9303211--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ATLANTIC OCEAN
BAYS
CENOZOIC ERA
COASTAL REGIONS
COASTAL WATERS
DATA ANALYSIS
DEPOSITION
DEVELOPED COUNTRIES
EROSION
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
MAINE
NORTH AMERICA
OFFSHORE SITES
QUATERNARY PERIOD
SEAS
SEDIMENTS
SEISMIC SURVEYS
SHORES
SURFACE WATERS
SURVEYS
USA