OVERWASH STUDIES AT CAPE LOOKOUT NATIONAL SEASHORE
To our knowledge, no studies had been done on the short-term ecological effects of overwash as they relate to the whole barrier-island system before our work, which was first described in the 1970 Annual Report of the Office of Natural Science (Godfrey 1970). Yet the overwash process is the key to understanding how low barrier islands can survive a slowly rising sea level (Shepard 1963).
The boundaries of Cape Lookout National Seashore, where we began our studies as part of a program initiated by its first Superintendent, Mr. Thomas Morse, encompass the southern half of the Outer Banks from Ocracoke Inlet to Beaufort Inlet (Fig. 9). Shackleford Banks (Fig. 10A) is separated from Cape Lookout by Barden Inlet, from which it extends west to Beaufort Inlet. The island can be divided into a western half, with large dunes and a typical maritime forest, and an eastern half which is low, flat, and covered with grass and shrubs, although it was wooded in the last century. North of Shackleford, across Back Sound, are the towns of Beaufort and Harkers Island.
The focal point of this seashore is the triangular Cape Lookout (Fig. 10B) which has had a history of dramatic reorientations to be discussed later. Development of the cape consists of scattered houses, a Coast Guard station, a marina, and the Cape Lookout Lighthouse, dating from 1859.
Core Banks, the major portion of Cape Lookout National Seashore, arcs northeastward from Cape Lookout toward Cape Hatteras. Its characteristic features are a wide berm, low dune lines, strips of grassland behind the dunes, with shrub thickets and a few hammocks scattered along its length, and extensive salt marshes behind the barrier (Fig. 10C). Core Banks is broken today by "new" Drum Inlet, created by the U.S. Army Corps of Engineers just south of "old" Drum Inlet, a natural opening which closed in 1971 (Fig. 10D). The island stretches northeastward from the wide shoals behind old Drum Inlet to the site of Swash Inlet, which has opened and closed repeatedly, and separates right and the beach on the left. Note the extensive barren flats that are awash at high tide. (G) Portsmouth Village and Ocracoke Inlet. (H) Ocracoke Island and the start of Cape Hatteras National Seashore. The straight patches of grass in the foreground are stabilization projects. Core Banks from Portsmouth Island (Fig. 10E). This latter island (Fig. 10F) differs from Core Banks in that it has an exceptionally low and wide stretch of sand between the berm and the salt-marsh islands behind. These barren, often flooded flats are widest opposite Portsmouth Village, now abandoned except for summer residents, at the northern end of the seashore (Fig. 10G). Portsmouth Village was the largest town on the Outer Banks in the early and mid-1800s; its unique history was recounted by Holland (1968). Beyond Ocracoke Inlet lies Ocracoke Island (Fig. 10H) and Cape Hatteras National Seashore with its roads and man-made dunes.
In contrast to Cape Hatteras National Seashore, the islands of Cape Lookout are largely in their natural state except for a few fishing camps and the tracks of beach vehicles. The only heavily visited area is Cape Lookout, which is served by a passenger ferry. There are no permanent roads on these islands, nor bridges to them, so this seashore has been spared the development and stabilization programs common to other coastal areas. These conditions, then, afforded us the opportunity to study the natural processes of a barrier chain before any drastic alterations began.
The fact that dramatic changes have occurred on these islands over the last century is clearly evident from old maps and records, as well as from present-day field data. Figure 11A shows the appearance of Shackleford Banks and Cape Lookout in the mid-1800s. At that time, Beaufort Inlet was considerably wider than at present, Shackleford was almost completely wooded, and it was connected to Core Banks. Cape Lookout was an elongated point extending southward from the junction of Core Banks and Shackleford. In the late 1800s a series of severe hurricanes started a series of changes that have continued to this day. The storms tore down the protecting seaward dune ridge and permitted sand to start moving across Shackleford. Diamond City was severely damaged and soon abandoned. In the early 1900s the formerly extensive forest was being buried by moving sand dunes, causing great alarm (Lewis 1917). Engels (1952) was one of the first investigators to point out the changes that occurred on Shackleford and to suggest that these were due to natural events rather than to human activities. Nevertheless, Shackleford today shows definite changes from a century ago (Fig. 11B). The end of the island has extended into Beaufort Inlet, following the typical pattern of spit growth. Only a small remnant of the forest remains on the western half, although most of the migrating dunes have since been stabilized by natural means. In 1933, a severe hurricane broke open Barden Inlet, which has since been dredged yearly.
Cape Lookout changed more dramatically than Shackleford, in part due to a jetty built out from its western side in the early 1900s. The Cape changed from a narrowly elongated triangle to a more equilateral triangle. The western point moved west as a result of the jetty. Cape Point retreated somewhat and also moved eastward. Dune lines which represent the old cape orientation are being truncated where they meet the beach on the southwest side (Fig. 130). These are the highest dunes of the cape and the site of World War II gun mounts, which are now falling into the sea. The cape has not lost total land area through this erosion. Sand has simply shifted from one point to another, in relation to continuing beach processes.
Despite the dramatic changes that occurred on Shackleford and Cape Lookout, many other areas of the seashore have undergone relatively little rearrangement since the first accurate maps were made in the mid-1800s. Topographic maps from that time, made by triangulation, are not exactly the same as modern maps made from aerial photographs, but they show features remarkably similar to those seen today (Fig. 12). The marshes and creeks are almost the same, as are the wide beaches with scattered woodlands. Considering the position of the beach, however, and taking into account the inherent errors in comparing old and new maps, it is clear that the barrier chain has retreated from its position in 1850. Yet, the physiography of the islands has remained the same, and it is this sameness over time in an environment of constant change that leads one to suspect that stabilizing forces are at work on the islands.
Last Updated: 21-Oct-2005