Paper No. 16-0
GEHRELS, W. Roland1, KIRBY, Jason R.1, NEWNHAM, Rewi M.1, BLACK, Stuart2, EVANS, Hywel3, ACHTERBERG, Eric P.3, and BELKNAP, Daniel F.4, (1) Dept. of Geographical Sciences, Univ. of Plymouth, Plymouth, PL4 8AA, United Kingdom,, (2) Postgraduate Research Institute for Sedimentology, Univ of Reading, Reading, RG6 6AB, United Kingdom, (3) Dept. of Environmental Sciences, Univ. of Plymouth, Plymouth, PL4 8AA, United Kingdom, (4) Dept. of Geological Sciences, Univ. of Maine, 111 Bryand Global Sciences Bldg, Orono, ME 04469-5790

This study establishes three high-resolution sea-level records based on foraminiferal and chronological analyses of saltmarsh peat sequences with the aim to extend back in time observational records of sea-level change. We report on records from Wells and Machiasport (northern Gulf of Maine) and Chezzetcook (Atlantic coast of Nova Scotia). The relationship between distributions of foraminiferal species and elevation on the modern saltmarsh surface is quantified by regression analyses and applied to fossil foraminifera in cores to reconstruct former heights of the saltmarsh surface in relation to tide levels. The peat sequences are dated by 210Pb, 137Cs, 206Pb/207Pb and AMS14C. We also use pollen markers (primarily Ambrosia) and historical archives to date the onset of land clearing subsequent to European settlement in the late 18th century. Our results indicate that, along the coast of Maine, sea level has risen by 30-40 cm since 1800 AD. A short-lived oscillation occurred in the 18th century. The sea-level record from Chezzetcook provides the highest resolution. Here, sea level rose by about 10 cm in the second half of the 18th century, but only by about 5 cm during the entire 19th century. Since 1900 AD, sea level has risen by about 35 cm. The 19th century slowdown of sea-level rise is also apparent in the Maine sea-level records albeit not as clearly pronounced when error margins are taken into account. The rates of 20th century sea-level rise agree with tide-gauge records. These rates are unprecedented in the last millennium and correspond with hemispheric (and global) climatic warming.

GSA Annual Meeting, November 5-8, 2001
General Information for this Meeting
Session No. 16
America's Coastal Crisis—Providing the Geoscience Information Needed to Conserve and Protect Coastal Resources
Hynes Convention Center: 112
8:00 AM-12:00 PM, Monday, November 5, 2001

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