At the nearly 3,000-acre First Landing State Park in Virginia Beach, people can traverse trails meandering through landscapes of forest, swamp and beach.
But many visitors don’t stop to think about the forces that shaped the land beneath, said geologist Rich Whittecar, an emeritus professor at Old Dominion University.
Whittecar has made it his mission to learn more about the geological history of the Cape Henry area, including the state park.
The land is marked by a series of sandy ridges extending toward the coast in a sort of corduroy pattern. Whittecar wanted to know more about how and when they formed.
After years of fieldwork, his team recently found out the answer: These sand dunes began appearing about 5,000 years ago, carved by erosion and sea level rise from melting glaciers after the last ice age ended around 11,000 years ago.
“When the oldest ridges were forming here, it was about 500 years before the Egyptians started building the big pyramids,” Whittecar said.
The researchers are working to finalize a formal paper by the end of the year. They say the new information about Virginia Beach’s northernmost point can not only shed light on its past, but also offer a window into its future amid rapid climate change.
“I hope people can put together some more of a long-term picture of what is happening here,” Whittecar said.
His initial fascination with Cape Henry stretches back decades, when he tagged along on a soil survey as a young professor.
At the time it was hard to date the dunes because researchers used radiocarbon dating, which relies on organic material that is not as common in sand. Scientific advances now allow for a different process, called optically stimulated luminescence.
A few years ago, Whittecar’s “squad of graduate students” began digging up sand dunes at 11 sites throughout First Landing State Park, reaching about 6 feet underground to find material long buried by time.
“We needed to come out and dig a hole big enough to get my body down into this and pound a tube into the side,” he said.
They wrapped sand samples in aluminum foil to shield them from outside light and sent them to a lab for the luminescence method.
Lab technicians peer into trillions of atoms in a grain of sand, looking for evidence of ionizing radiation that sand absorbs as it decays under new layers.
By measuring the crystal structure of these particles, scientists determine the amount of time that’s passed since the sample last saw the light of day.
The age of the ridges at First Landing ranges from 5,000 years along the south side, near Linkhorn Bay, and gradually decreases as they stretch closer to the coastline. The newest crest, around the campground, is only 125 years old.
There are several types of dunes in the area, Whittecar said. Most are “low, long, continuous, skinny ridges,” which formed over a long period of time.
Some jut up more irregularly, reaching about 30 feet in height.
“The big, tall, knobby ridges are ones that we're pretty sure happened when the ocean was cutting back and eroding into the beach,” he said. “As it did that, it kicked up a lot of more sand, and that sand blew back and formed the ridges behind it.”
The trails people travel around the state park are largely those tall, knobby dunes.
Finally, there are larger, 100-foot dunes that formed much later around Fort Story and became prominent to early navigators in the Colonial era.
“As the ships would come up and see these big, tall dunes at Cape Henry, they'd say, ‘Oh, this is where you turn and go into the mouth of the Chesapeake Bay,’” Whittecar said.
Professor Tom Allen, chair of ODU’s department of political science and geography, got involved to help build a precise digital map of the area.
He used lidar, a laser-based aerial surveillance technique, to “basically paint the ground with elevation points” and identify the shape and size of the dunes.
Looking at these data points is like looking at the rings of a tree trunk, he said, with signals embedded that could point to evidence of storms or erosion.
Allen said those historic patterns can help officials determine what might happen next, as climate conditions continue to change.
“The better we can understand Cape Henry, the better we can predict and manage what we have,” he said. “It's all trending to natural curiosity. But also, there's a kind of stewardship, and inherent beauty in understanding the environment here.”
