The wide mouth of the Neuse River and broad expanses of the Pamlico and Albermarle Sounds are products of the thin and fragile sand banks - the Outer Banks - that line the coast. All the water that pours down from the hinterlands must eventually escape to the sea, and it does that through the inlets that cut the banks at intervals - Oregon Inlet, Hatteras Inlet, Ocracoke Inlet, New Drum Inlet, New-Old Drum Inlet and Ophelia Inlet. Only one of these inlets - Ocracoke - has existed for all of the recorded history of the banks, and one - Ophelia - just opened in 2005.
The authors of Past, Present and Future Inlets of the Outer Banks Barrier Islands, North Carolina have identified close to forty more inlets that have opened and closed through the years. Probably the most important was Roanoke Inlet which provided access to the sound for the earliest North Carolina colonists who settled Roanoke Island and later disappeared with almost no trace. This inlet closed in 1811, with dramatic results. The vast area of swampland and shallows that lay between Roanoke Island and the mainland eroded away, forming Croatan Sound, as the outflow of Albermarle Sound sought a new route to the sea. In 1846 a hurricane opened Oregon Inlet, which today provides an outlet for Albermarle Sound and the upper Pamlico.
Ocracoke Inlet has proven the most stable access to the sea. It is the natural outlet of the Neuse River by way of a geologic formation known as the paleo-Neuse River, a watercourse during the Last Glacial Maximum of 20,000 years ago. At the time, so much water was tied up in ice that ocean levels were considerably lower and the current sounds were dry land. These old formations die hard, and the relatively deep water of Bigfoot Slough and the inlet itself are relics of another old watercourse, Pamlico Creek. Even the Tar and Pamlico Rivers once exited through Ocracoke Inlet, back in the days of pre-history. For all its geologic stability, Ocracoke Inlet is still an area of continual shoaling and movement. Portsmouth Village on the south side was once a thriving commercial port, but continual shoaling has left it deserted and abandoned.
The white paper "Past, Present and Future Inlets of the Outer Banks Barrier Islands, North Carolina" includes much fascinating history on all current inlets plus details on some of the recent short-lived ones, like Buxton Inlet, which opened in 1962 and was quickly closed by the U.S. Army Corps of Engineers, and Isabel Inlet of 2003 which also was closed by the Corps of Engineers. Isabel had opened once before, in 1933, and closed naturally. During the earlier opening, a bridge was built across the inlet, and its pilings were uncovered in 2003.
The history of Drum Inlet shows the changeable nature of the banks. Drum Inlet opened around 1899 but closed naturally by 1919. A major hurricane reopened it in 1933 , and in 1938 the Corps of Engineers started dredging it to try to create a navigable channel for local fishermen. They never achieved much success, and by 1971 the inlet was almost completely closed. At that point, the Corps of Engineers blasted and dredged a new inlet a few miles to the south, aptly named New Drum Inlet. However, this inlet shoaled so rapidly that no commercial vessel ever made use of it. In 1999, Hurricane Dennis reopened the original Drum Inlet, which is now known as New-Old Drum Inlet. In 2005, Ophelia cut Ophelia Inlet near New Drum Inlet, and now the two are close to merging. Because all this has happened on the deserted Core Banks, little has been made of it, but if this opening and closing of inlets happened north of Ocracoke it would be a major problem for the tourism industry that drives the banks economy - just as Buxton and Isabel were.
The paper includes good discussions of how inlets are formed (commonly by hurricane overwash in areas of low sand volume and soft underlying geology) and where the potential hotspots for new inlet formation lie. All of the area south of Oregon Inlet, including most of Pea Island, is geologically susceptible to inlet formation. Oregon Inlet itself drifted two miles south before it was corsetted by jetties beneath the Bonner Bridge, and even now is gnawing away at the southernmost pilings and jetties. It is only a matter of time before this bridge, which has already exceeded its expected lifespan, is removed or collapses into the sea. Likewise, the whole northern end of Ocracoke Island presents opportunity for inlets. The location of Buxton Inlet will likely see reopening at some point. The island in this vicinity has receded 2,500 feet since 1852, 76% of its original width.
With rising oceans as the ice-caps melt away, an accelerated rate of erosion and inlet-opening can be expected for the Outer Banks. In addition, long stretches of the banks could erode to the point of collapse; in other words, parts of the banks could disappear altogether. Researchers are studying the collapse of parts of Dauphin Island in Alabama and the Chandaleur Islands in Louisiana, barrier islands similar to our Outer Banks, to understand the potential changes we may see. Certainly a fragmentation of the banks would mean more salt water and tidal action in the sound. Much of Hyde and mainland Dare Counties would become marshland. And the Outer Banks as we know them would cease to exist. Maintaining highway communications and even electric power along the banks would be next to impossible in a world of constantly opening and closing inlets and multi-mile wide sections of completely submerged banks.
Geologic changes are slow to the human eye, but change is no doubt coming to the Outer Banks at an accelerating rate. What has happened in the past, and what may happen in the future, are matters of interest to Neuse River sailors. "Past, Present and Future Inlets of the Outer Banks Barrier Islands, North Carolina" is a fine piece of research that is worthy of study.
Another interesting paper on this subject is The North Carolina Outer Banks Barrier Islands: A Field Trip Guide to the Geology, Geomorphology, and Processes by a group of distinguished scholars at Eastern Carolina University and the University of Pennsylvania. This paper includes some great charts and diagrams of the geological progression of the Neuse River lowlands. It also explains the efforts made ever since the 1930s to stabilize the banks by building artificial dune ridges - the fractured and destroyed remnants of which are so obvious along Highway 12 north of Ocracoke and on Pea Island.