Editor’s note: This is the 4th in a series of articles covering the region’s dramatically changing coastline. Click here to see all of the articles.
In April of 2007, a powerful storm on Patriots’ Day caused a break near the center of Norton Point Beach, a barrier beach that runs along the southeastern tip of Martha’s Vineyard dividing Katama Bay from the Atlantic. With this breach in the two-and-one-half mile beach, Chappaquiddick became entirely severed from the Vineyard.
Since that 2007 storm, the break—which at its widest measured nearly a quarter-mile across—continually migrated to the east, and caused a variety of problems in Vineyard waterways. “The break at Norton Beach affected the whole of Katama Bay and the inner harbor,” says Charlie Blair, Edgartown’s harbormaster. “The current ran up to three knots.” Blair likened the inner harbor at the time to Woods Hole Passage, a fast-moving and potentially treacherous waterway off Falmouth that most ships avoid.
In the storm’s immediate aftermath, the On Time ferry, which regularly transports passengers the 527 feet between Chappy and Edgartown, found itself being continually swept southward to the Edgartown Yacht Club—some 500 feet—as it attempted to make its way across the channel. To remedy this, the ferry owner had to install a stronger engine to withstand the new, stronger current.
Over the years, the effects levied on the coastline were even more dramatic. The beach at Wasque Point—Chappaquiddick’s south-easternmost tip—and the nearby swan pond were washed away, and stairs and boardwalks leading to the beach were destroyed or swept into the ocean. The powerful currents from the breach also unearthed a few things that had long been hidden or buried. “Divers were finding 150-year-old bottles lying on the bottom in plain sight,” Blair recalls.
After nearly eight years, however, the breach is no more! On April 2, 2015, the breach, which had migrated all the way to Wasque, became completely closed as the Norton Point Beach reattached to Chappaquiddick. By the end of the month, vehicles were once again allowed to travel over the beach from Chappy to Edgartown—with a required permit.
Britt Raubenheimer, a scientist specializing in applied ocean physics and engineering at Woods Hole Oceanographic Institution (WHOI), commented on the dramatic geologic change. “It was very interesting to see how fast the barrier grew after the closing, changing from being always open to being closed even at the highest tides-—in just a day. The speed of sand piling up has been seen before, and was expected, but remains amazing to me.”
This scenario may seem an anomaly, but a quick study of the Vineyard’s geological history reveals that this break in the beach has occurred several times in the past 150 years, continually linking and separating Chappaquiddick from the main island. According to Tom Dunlop, who has written about the breach for Martha’s Vineyard Magazine and just published a book on the Chappy Ferry (see p. 120), the earliest recorded breach took place in 1856. A map of the Vineyard from 1892 shows a considerable breach, and additional maps and postcards from the past century show the beach in various states. The coastline has been changing—constantly.
What is it about Norton Point that inspires this continuous cycle of barrier beach breaks—and subsequent restorations? Raubenheimer offers a simple answer. “The tides in Vineyard Sound (the waters on the north and western sides of the Vineyard, which flow into Edgartown Harbor) are very different from the Atlantic Ocean tides (to the south of the island where Norton Point Beach is located),” she says. “They are three hours apart meaning that one side of the barrier beach has higher water on it than the other.” This higher water flows “downhill” from north to south, or south to north, depending on the tides, causing the beach to erode—and eventually breach.
Raubenheimer adds that breaches can occur—and then widen—at a rapid clip. She recalls an experiment where an artificial breach was created and due to currents in the area it widened to five times its initial dimensions within an hour’s time.
Another question to ponder is how the breach healed itself. Steve Elgar, another WHOI scientist who has been studying the breach with Raubenheimer since 2011, offers a response. “It all comes down to friction,” Elgar says. “After the initial breach, the currents going into Katama Bay were faster than those coming out.”
This situation, Elgar says, may have resulted in sand being deposited in the breach, rather than being swept out to sea in faster currents.
Though the two scientists understand this process, neither Elgar nor Raubenheimer are sure exactly where that sand came from. It could have come from shoals in the bay or from offshore shoals, they speculated, or from sand being moved along Norton Point Beach from further down the shore.
Finally, the question many in the area are now asking is how long will it be until Norton Point Beach is breached again? “It could be another 30 years—or it could be a year or two,” Raubenheimer says. “It all depends on the tides and the weather.”
Christopher Setterlund is a freelancer writer from South Yarmouth.