Riggs identifies two Coastal Zones in North Carolina. Ocracoke belongs in the Northern Coastal Zone which extends from the Virginia border to Cape Lookout. Unlike the Southern Coastal zone which is "underlain by rocks that range in age from 145 to 2.6 million years," the Northern Coastal Zone is filled with "marine mud, muddy sand, sand, and peat" which buried the older rock "to a depth of 50 to 250 feet."
|The Outer Banks, from Apollo 9|
Below is a summary of Dr. Riggs' explanation of the evolution of the Northern Coastal Zone:
- Ca. 9,000 years ago: Sea level rise flooded the paleo-Tar and Neuse River valleys, "forming a series of small narrow estuaries." At this time the mainland ocean shoreline was a few miles east of the present Outer Banks. Riggs speculates that there might have been barrier islands situated close to the shoreline.
- By ca. 7,000 years ago Pamlico Sound formed as the result of continued sea level rise. Precursor barrier islands formed "east of the modern Outer Banks." What we know today as the Outer Banks did not exist at that time.
- Over the next few thousand years the shoreline migrated to the west. By ca. 1,100 years ago (ca. 900 CE) barrier islands existed close to the location of the modern Outer Banks.
- Beginning ca. 1,100 years ago much of the southern section of the Outer Banks, from Cape Hatteras to Ocracoke Inlet, collapsed as the result of storms, creating back-barrier shoals.
- By about 500 years ago (just prior to the arrival of the first Europeans) the modern Outer Banks barrier islands re-formed. During the "Little Ice Age" (ca. 1300 to ca. 1850) numerous inlets, probably the result of increased storm activity, separated the islands of the Outer Banks. Today, there are only three major inlets along the Outer Banks: Oregon, Hatteras, and Ocracoke.
This month's Ocracoke Newsletter is the dramatic story of life-saver Rasmus Midgett and his rescue of the crew of the barkentine Priscilla in August, 1899. You can read it here: http://www.villagecraftsmen.com/news052116.htm.