Dune erosion on Bear Island

Figure 7. Hurricanes in the 1990s eroded the dunes on the east end of Bear Island. (Photograph by the author. More about the photograph)

Figure 7 shows that not all of the barrier islands are flattened when hurricanes make landfall over them. This photograph shows the beach and seawardmost dunes of Bear Island after five hurricanes battered them in two years. The remnants of dead maritime thicket plants in the foreground show that the primary dune has been destroyed here, but the cliffed dune in the background shows that the primary dune was not completely destroyed everywhere. In fact, if you look closely at that dune, you will see that its seaward face is redeveloping a slope in front of the cliff formed during the hurricane. The sand for the slope came partly from collapse of the cliff, but some of the slope’s sand was also carried to the cliff face by wind. This wind-borne sand was winnowed out of the beach after the hurricanes and has begun to rebuild the dunes.

Thus do natural processes gradually rebuild barrier islands after storms flatten them. The recovery period is long relative to the erosion time, but gradually these islands will rebuild most of their characteristic features. It helps if they have a large sand supply to use in the rebuilding. Different barrier islands along our coast are built of different amounts of sand. (This is explained in two other field trips in this series, Large Sand Volume Islands and Small Sand Volume Islands.)

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