Intense landfalling hurricanes can result in substantial loss of life and resources. Intense hurricane strikes also result in significant alteration of coastal sedimentary environments, and in appropriate depositional settings a geologic record of these events can be preserved.
Potential links between human-induced climate change and the frequency and intensity of tropical cyclones and the recent concentration of resources and population in areas where intense hurricanes may strike necessitate examination of decadal-to-millennial-scale variability in hurricane activity. I use sediment cores (Figure 1) and subsurface profiling to reconstruct the overwash history of backbarrier salt marshes (Figure 2) and coastal ponds and extend the historical record of intense landfalling hurricanes into the prehistoric period.
Figure 1: Jeff Donnelly (right), Nat Logar (center), and Peter Cleary (left) vibracoring in a Bridgeport, Connecticut salt marsh.
Figure 2: Photograph of overwash sand deposits associated with intense hurricane strikes in 1938 and 1815 within salt marsh peat from Succotash Marsh, Rhode Island.
Six overwash fans deposited since the early 1300 A.D. in a southern Rhode Island backbarrier marsh have been attributed to intense hurricane strikes (Figure 3). In a similar study from the southern New Jersey coast, we attributed overwash fans to the Ash Wednesday Nor'easter of 1962, an intense hurricane strike in 1821, and an intense hurricane between 1278 and 1438 A.D.
Ongoing work includes developing records from a network of sites from the northeastern United States in hope of providing a regional synthesis of intense storm activity. In addition future work includes developing records from Puerto Rico and Florida. Additional related areas of research include examining sedimentary records river flooding and isotopic analysis of tree rings that may provide additional information on storms of the past.
Figure 3: Stratigraphic cross-section of Succotash Marsh, RI based on a transect of vibracores. The labels on the overwash deposits are the best estimate of the date of deposition. Vertical lines show core locations with core numbers noted above. (click for larger image)
