Paleotempestology Studies at UF

Paleohurricane (i.e., paleotempestology) studies provide important information about the frequency of hurricane strikes in a region and changes in hurricane patterns in a region may provide information about the regional paleoclimate. Although data on historical hurricanes extend back several centuries, reliable data from NOAA only exists from the late nineteenth century. To get an idea of the true frequency of hurricanes in a region, a paleorecord of hurricane activity is needed that spans several thousands of years. Insurance companies are beginning to realize this and are starting to fund scientific research that examines paleohurricane frequency (Michaels et al., 1997).

Coastal lake and marsh sediments provide chronologies of the most severe hurricane events. Lakes, lagoons, and marshes located just beyond coastal barrier dunes can record hurricane events in their sediments when severe storms cause high surges, coastal flooding and frequent overwash of barrier dunes. Often sand is deposited during these events into these coastal depositional environments. The presence of these sand beds has been used as a proxy indicator of hurricane landfalls (Lui and Fearn, 1993 and 2000). However, the conclusions drawn from these studies have been called into question, as there are many additional processes besides hurricanes that can deposit sand in these environments.

What we’re doing at UF

Sampling in Oyster Pond, St. Vincent Isl. Sampling in the Salt Marsh, St. Vincent Isl. X-radiograph of salt

marsh core showing

sandy hurricane bedding

My students are currently examining the sedimentological record of hurricane deposition along the Apalachicola Bay area of the Gulf Coast (St. Vincent Island and Alligator Point, Franklin County). This region is regularly impacted by tropical storms and hurricanes; 56% of the hurricanes to hit the Florida panhandle from 1885 to 1984 occurred in the Apalachicola Bay area. This frequent and well-documented history of hurricanes makes this an ideal environment in which to look for proxy records in coastal sediments of hurricane landfalls. Whereas coastal lakes have been the preferred environment from which to evaluate paleohurricane deposition, we are conducting a systematic study of the environments (lake, supratidal, intertidal, or subtidal) that can best preserve a proxy record (e.g., marine microfossils; sand layers; marine organic carbon) of hurricanes making landfall.

Based on the results of these studies, we plan to collect longer cores along a broader region of the coast in an attempt to better constrain changes in hurricane frequency over the late Holocene.

Liu, K.B. & Fearn, M.L. (2000) Reconstruction of prehistoric landfall frequencies of catastrophic hurricanes in northwestern Florida from lake sediment records. Quaternary Research, 54(2), 238-245.

Liu, K.B. & Fearn, M.L. (1993) Lake-sediment record of late Holocene hurricane activities from coastal Alabama. Geology, 21, 793-796.

Michaels, A., Malmquist, D., Knap, A., and Close, A. (1997) Climate science and insurance risk. Nature, 389, 225-227.