Paleotempestology      New England Hurricanes     Sea Level Rise

Tidal surge and overwash depostion animation.

Tidal surges from large storms and hurricanes deposit sand.
Ocean to the left and tidal lagoon to the right form a barrier-beach salt marsh.

Jeff Donnelly, a postdoctorate currently working out of Woods Hole, Massachusetts, and Rick Lederer, a former Masters student, have completed initial work on reconstructing the history of intense hurricanes striking the east coast from New Jersey to Maine.

Cores of saltmarsh sediments contain layers of sandy overwash deposits between layers of peat. (See below.) The animation on the right shows the working model for the deposition of these layers as the salt marsh grows upward and landward in the face of continuing sea-level rise. Transects of vibracores allow the mapping of the overwash fans. We have matched the upper-most overwash fans to aerial photos of the fans after known hurricanes and then matched the lower sand layers to other historically known storms. Prehistoric sand layers are radiocarbon dated and provide records of possible prehistoric storms. The salt marsh cores provide records of 600 to 1000 years and add key information for calculating the long-term return rates on intense hurricanes that make landfall. This research is sponsored by the Risk Protection Institute of the Bermuda Biological Laboratory for Research.

Photo of overwash sand deposits in sediment core Photo of trio extracting sediment using vibracore equipment

Overwash Deposits
The contrasting peat and sand layers at 18 and 33 centimeters indicate overwash deposits.
Click to enlarge. (60 KB)

Vibracore Sediment Extraction
Left to right, undergraduate Peter Cleary, graduate Nat Logan and post-doctorate Jeff Donnelly.
Click to enlarge. (182 KB)

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Coastal Studies     Geoarchaeology     Paleoclimates     Vegetation Dynamics    

Paleotempestology      New England Hurricanes     Sea Level Rise