{"id":185040,"date":"2025-03-24T13:05:46","date_gmt":"2025-03-24T13:05:46","guid":{"rendered":"https:\/\/nauticalcharts.noaa.gov\/updates\/?p=185040"},"modified":"2025-03-31T19:56:25","modified_gmt":"2025-03-31T19:56:25","slug":"ancient-river-systems-glacial-grooves-and-steep-cliffs-discovered-near-cape-fear-north-carolina","status":"publish","type":"post","link":"https:\/\/nauticalcharts.noaa.gov\/updates\/ancient-river-systems-glacial-grooves-and-steep-cliffs-discovered-near-cape-fear-north-carolina\/","title":{"rendered":"Ancient river systems, glacial grooves, and steep cliffs discovered near Cape Fear, North Carolina"},"content":{"rendered":"\n

A View into the History of the Cape Fear Region\u2013Tens of Thousands of Years into the Past<\/h3>\n\n\n\n

By Cmdr. William Winner<\/strong><\/h4>\n\n\n\n

Over the spring and summer of 2024, NOAA Ship Ferdinand R. Hassler<\/em> surveyed an area southeast of Cape Fear, North Carolina. This area is unique to the East Coast of the United States\u2014whereas most of the East Coast\u2019s seabed is sandy and has large areas of sand waves, this area does not have as much deep sand cover and instead features exposed underlying bedrock.<\/p>\n\n\n\n\n\n\n\n

\"An
An overview map showing the project area OPR-F324-FH-24.<\/figcaption><\/figure>\n\n\n\n

The area provides unique insights into what the Cape Fear region would have looked like tens of thousands of years ago. We can see evidence of ancient river systems and lakes, steep cliffs, and glacial grooves and channels visible in the rock surfaces. Based on the approximate underwater shoreline depths, our estimates are that these areas were flooded around eight to ten thousand years ago, based on prior research as seen below in the post-glacial sea level rise graph.<\/p>\n\n\n\n

\"A
A graph showing sea level rise at the end of the last glacial episode based on data from Fleming et al. 1998, Fleming 2000, and Milne et al. 20051<\/sup>.<\/figcaption><\/figure>\n\n\n\n

Ancient River Systems<\/h4>\n\n\n\n

This area is rich in palaeochannels. Palaeochannels\u2014literally meaning “old channel”\u2014are generally used to refer to rivers that are no longer in use above ground.  Either the river no longer flows there because of a change in water level or change in the direction of the river, or the river has been filled in fully.<\/p>\n\n\n\n

We believe that, due to the Gulf Stream predominantly moving water from the southwest to northeast, the Cape Fear ridge provides a natural barrier for sand. This results in sand building up along the Cape Fear ridge and not allowing the sand to continue over the ridge into the area of exposed bedrock.<\/p>\n\n\n\n

This provides unique opportunities to see where rivers would have run in times past. As seen in the images below there is clear evidence of previous river systems in the bathymetric data.<\/p>\n\n\n\n

Additionally, the area is sediment starved because the adjacent rivers have low flow that feeds into the back-barrier island bays rather than the ocean, and currents prevent sediment transport around the capes that make the northern and southern boundaries of Onslow Bay, Cape Lookout and Cape Fear, respectively. The lack of sediment input means hard bottoms are exposed in much of Onslow Bay, and most sediment comes from erosion of local rock2,3<\/sup><\/p>\n\n\n

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