Small and large sand volume islands

On this field trip, we'll visit Bear Island and Bogue Banks. (Satellite image from NASA with map drawn over top. More about the map)

This field trip follows another in this series, Small Sand Volume Islands. Readers should plan to take these trips sequentially, to compare the two types of islands. The thesis of both trips is that the volume of sand that comprises a coastal barrier island is an important predictor of storm damage risk to human residential developments built upon them. In the small sand volume trip we visited one undeveloped island (Masonboro) and one developed island (North Topsail). We saw that the environmental processes on each island were similar, but on Masonboro the storm damage associated with Hurricanes Dennis and Floyd was quite hard to recognize. On Topsail, however, the same processes had destroyed manmade dunes, roads, houses, and beach access structures.

In this trip we will visit an undeveloped island (Bear) and its neighboring developed barrier (Bogue Banks). Both of these islands have substantially greater sand volumes than Masonboro or Topsail. The reasons for the difference are found in history and geography. The history of North Carolina coast is one of sea level rise and fall. Sea level is rising now, but most people are surprised to learn that the long-term trend of sea level has been down since the Atlantic Ocean opened. (For a discussion of sea level change see the virtual field trip entitled Sea Level Rise, Erosion, and Plants.)

During previous periods of sea level decline, old shorelines were left behind to form sandy ridges on the coastal plain. Eight major ridges of this type have been identified and named, but many more exist. In some places these old shorelines reach the present coast, and their sand can be incorporated into the modern barrier islands. That event has happened on both Bear Island and Bogue Banks. In addition, these two islands have developed close to the mouth of the ancestral Neuse River and so have had sand from that source as well.

As you will see, Bear Island and Bogue Bank have high dunes, sandy ridges, and a relatively stable history. Bogue Bank has been successfully developed for residential use. Bear Island has not been developed, not because it is unsuitable for development but because it is part of the state park system. This trip will take you to these high sand volume islands, so you can see for yourself what they are like.

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