Geology in Motion

The Foundation of Surfing

by Meredith Haas


Surfing in New England often means donning thick, hooded wetsuits, navigating the occasional snow-covered beach, and avoiding rocks—conditions that explain why surfing here was slow to catch on when the sport first took hold in the warmer waters and sandy beaches of California and Hawaii before gaining broader popularity in the 1960s.

It was hard to believe, then, that there was even surf in Rhode Island, or anywhere along New England’s rocky coast.

Photo Jesse Burke

Now, several decades later, on any given day of the year, whether conditions promise ankle-biter waves or overhead sets, you can usually find suited-up surfers making their way out to popular surf spots, including a south-facing reef that extends several hundred yards between the Ocean Mist and Matunuck Point in South Kingstown.

Known for its consistent left or right breaks of either soft peeling waves or heavier, faster sets when big south or southeast swells roll in, this cobblestone reef is an extension of the Matunuck headland and the remnant of a glacier that retreated over 18,000 years ago, says Bryan Oakley, a geoscientist at Eastern Connecticut State University.

As surfers wade out to these breaks, each careful step over the various contours and sizes of cobblestones and boulders speaks to the geological history from which all surfers, including windsurfers and kiteboarders, benefit.

Long before surfing came to Rhode Island, and long before the first wave was ever ridden nearly 3,000 years ago in Western Polynesia, waves have been crashing along shorelines that have contracted, expanded, and migrated from glaciers advancing and retreating, sea levels falling and rising, and plates within the Earth’s crust converging and diverging to form the landmasses of today.

In short, surfers have been benefiting from millions of years of weathering and tectonic activity that have subsequently shaped coastlines and their respective breaks. And while Rhode Island may not boast large, powerful waves like those found at Mavericks on Northern California’s coast or the tubes of the Banzai Pipeline on the North Shore of Oahu, Hawaii—where waves can crest over 25 feet—its surfing community, like all others worldwide, is tied to the local geology—specifically, the topography of the seafloor.

“There’s a direct correlation between geology and surfing,” says Jim Turenne, a soil scientist with the Rhode Island Natural Resources Conservation Service and an avid local surfer, pointing to various surf spots in Rhode Island on an interactive soil map that identifies coastal composition as sandy, cobblestone —rocks that vary in size from four inches to a foot—or larger boulders. “The bottom tells you what kind of break it will be.”

Waves are the result of a domino effect of energy generated, mainly, by wind. The greater the speed of the wind, the longer it blows, and the greater the distance over which it blows (also known as fetch), the bigger the waves. As individual waves organize into sets traveling at the same speed, their quality is determined by the amount of time two successive wave crests pass through a fixed point, known as the swell period.

“As a general rule, the longer the swell period, the further the swell has traveled, allowing the swell to become more organized,” says Brian Caccioppoli, a local surfer and marine geology research assistant at the University of Rhode Island Graduate School of Oceanography (GSO). “In addition, the higher the swell period, the faster and more energetic the breaking waves will be at the shore.”

 

Local surfer Brian Caccioppoli heads out to one of the many surf spots in Rhode Island that formed over thousands of years.

Local factors, such as the direction of the swell, winds, and tides are also factors for creating quality surf, but it’s not until the swell interacts with the seafloor that it turns into breaking waves.

As a swell approaches the coastline and moves into shallow water, friction slows down the bottom of the wave as it meets the seafloor, while the top continues at the same speed, causing the wave to stand up—creating the wave face sought after by surfers—and spill over. This happens when the approaching wave reaches a water depth 1.3 times its height (the distance from trough to crest), which can happen abruptly or gradually, depending on the slope of the seafloor—the rate of the change in depth from the shore to the open ocean.

Areas along the West Coast or along volcanic archipelagos like Hawaii, for example, are associated with large, barrel-shaped waves that are achieved from prevailing winds traveling longer distances across the Pacific Ocean that quickly rise on steep slopes.

Jim Turenne, a soil scientist with the Rhode Island Natural Resources Conservation Service and an avid local surfer.

Because of the rapid change in depth, waves in these locations tend to break with more height and power. Breaks along the East Coast, on the other hand, do not generate as much energy—with the exception of hurricane-generated swells—because storms tend to travel west to east, traveling out to sea, and do not cover as great a distance across the Atlantic as they do in the Pacific.

In addition, the East Coast sits on a broad, gently sloping continental shelf that slows swell energy by dragging the wave over a greater distance of the seafloor. Rhode Island’s coast sits several hundred miles from the edge of the continental shelf with a slope that varies widely, making some areas unsurfable, such as the shoreline between Monahan’s Dock to Black Point in Narragansett that has a quick drop off to roughly 80 feet, making it too deep to produce any surf at that location, according to Turenne.

Swells that hit Block Island tend to be larger both because the island catches swells earlier, as it lies 13 miles south from the mainland, but also because its slope rises more quickly from 200 to 10 feet within several hundred yards.

“Tack two feet on to what we’re getting at Point Judith and that’s what they’re getting at Block Island,” Turenne says. The Ruggles break, however, which is located at the eastern end of Ruggles Avenue in Newport and behind the famous mansions of Bellevue Avenue, can hold 20-foot waves on a big swell, largely because of the underlying bedrock.

“When you get into Ruggles, you’re surfing on slabs of bedrock,” says Turenne. “It’s deeper water so it needs a bigger swell.”

Depth and Character

How a wave breaks is just as important as its size and is dependent upon the shape and type of bottom, or features of the seafloor.

“This is why Point Judith has [some of] the best waves,” Turenne says, pointing to the classic point break that juts out like a canine incisor at the intersection between Narragansett Bay and Block Island Sound, explaining that while it might not hold as heavy of a wave as Ruggles, it is more consistent. “If you look at the shoal, [waves are hitting that] and causing them to peel off, versus Narragansett Beach where it’s flat; there’s no structure at all to it, so it just dumps over and doesn’t peel.”

What Turenne is referring to is how wave energy refracts or is directed over different depths created by these bottom features.

Sandy beach breaks, like Narragansett Town Beach, or First and Second beaches at the edges of Newport and Middletown, behave differently from cobblestone reefs and rocky point breaks, as well as breaks over exposed bedrock like Ruggles or in Jamestown, because the bottom is more fluid and susceptible to change.

Storms and wave action shift and alter the depth at different points, making these types of breaks disappear and reappear with sand movement, especially along Rhode Island’s southern shore, which is more exposed to storms and higher wave energy.

Depending on how the sandbar builds and shifts, the break will change accordingly. A flat beach break, for example, is not ideal for surfers because the wave would crest and spill across the whole line at the same time (referred to as dumping or closing out), which often happens at Narragansett Town Beach.

“Sandbars are always changing,” says Turenne. “Sometimes Narragansett Beach is good, and other times it dumps over with no shape.”

Surfers generally look for peeling waves that break gradually to the left or to the right along the wave crest. This is achieved when one side of the wave is forced to break before another.

It’s like a car hitting the brakes on only one side, forcing the car to veer in the direction of its slower half, according to Tony Butt and Paula Russell in their book Surf Science. Waves will veer, or bend towards the slower section, creating a wave that’s surfable.

Although this can be achieved by sandbars, rocky points and cobblestone reefs offer more consistent breaks with often bigger and longer rides depending on the direction of the swell—one of the main features that sets Rhode Island apart for New England surfing. Due to its largely south-facing coastline, including Block Island, Rhode Island can catch most southern swells (Long Island tends to block southwest swells) that would otherwise bypass most of New England’s primarily east-facing coastline.

“The beauty of Rhode Island is that we can surf on just about every direction” of wind and swell, says Turenne.

Thousands of Years in the Making

Many of the 30-some-odd surf spots scattered between Westerly and Little Compton have been thousands of years in the making.

While beach breaks are largely the result of more modern processes such as everyday erosion of bluffs and headlands, the processes that create cobblestone and rocky breaks take a bit more time. Much of the underwater geology is glacial till—a mixture of gravel, clay, silt, and sand—that extends out onto the continental shelf, which turns into boulder and cobblestone fields as you get closer to shore.

This is a result of the advance and retreat of the Laurentide Ice Sheet, which formed during the most recent ice age in North America. This mile-thick expanse of ice extended from Canada and covered New England more than 20,000 years ago. As the ice sheet advanced, it picked up, crushed, and dragged layers of rock and soil underneath, moving boulders and other material like a conveyor belt toward the coast just beyond Block Island, where sea level was 300 feet lower than it is today.

The furthest reach of the glacier is marked by “terminal” moraines where debris of rocks and sediment collected by the glacier as it advanced was dumped at the outer edge of the ice. This is how Block Island formed, along with Long Island, Nantucket, and Martha’s Vineyard, which all lie along the same terminal line. Additional recessional end moraines formed at locations where the glacier paused its retreat and deposited a large amount of till in one location (like the Charlestown Moraine along Route 1).

“Glaciers, in addition to eroding and clearing out everything that was here prior to the last glaciation, deposit material directly from the ice or from meltwater in front of the glacier. When a glacier gets to its southern limit, or as it’s receding back north as the climate warms, it will form moraines at stillstands [where] the ice just sits at a place and even though it isn’t advancing forward, the ice within the glacier is still flowing forward and depositing lots of sediment directly from the ice at that location,” says Joe Klinger, another local surfer who is also a coastal geologist and environmental scientist with the consulting firm Ecotones Inc. Point Judith was formed in a similar way, he adds.

“Point Judith is interesting because it’s an end moraine in a complicated area where two sub-lobes of ice may have come together. One within Narragansett Bay/Buzzards Bay, and then another lobe of ice to the west. Point Judith is in the middle as well as at that glacial stillstand location,” he says. “That’s why Point Judith is what it is.”

As glaciers advance and retreat, they do so in lobes, or sections that move at different speeds and directions. As climate started to warm and the glacier moved back, the lobe to the west of Point Judith formed what is called the Charlestown moraine and other moraines associated with it, says Klinger.

“Out in front of that, all the water that was melting from the glacier was pouring towards the ocean as we know it today. Again, sea level was so low it was on the other side of Block Island, but all that meltwater was carrying glacial fluvial deposits, also termed outwash, and that’s what Matunuck is—sand, gravel, and cobble from meltwater outwash,” he says. “It’s very different from Point Judith, and [it’s] what gives Matunuck its specific surfing setup because you have an outwash plain generally sloping south into the ocean. So, when the waves come, they’re coming up that cobble bottom and [they] make the beautiful wave that is Matunuck.”

“It’s mostly rounded rock fragments, which is why Trestles is such a great wave,” says Turenne, commenting on one of the three breaks off Matunuck that resembles its famous Californian namesake. “It juts out at the right spot, making it peel right off.”

As the glacier continued to retreat up through Narragansett Bay, it exposed channels in the old sedimentary basin that had been scoured and carved from the weight and pulsing of the ice sheet as it advanced south and receded back north, which formed the East and West passages around Conanicut Island.

“In general, the whole state was covered by ice, but the ice falls into two general categories—‘clean’ and ‘dirty’ ice. Areas with lots of boulders and till (glacial sediment of very mixed grain sizes) were in the dirty ice zone, and areas in the clean ice zone tend to not have boulders and till deposited as the ice melts,” says John King, professor of geological oceanography at GSO, explaining why some of the bottom features differ between the eastern and western half of the state. “In the eastern part of the state, the dirty ice zone of comparable age to the Charlestown moraine was well south of Jamestown and Newport, and those areas were being eroded by clean ice scouring bedrock. There are different things happening near the terminus of a glacier than there are further back beneath the ice sheet. Further back is mostly erosion, whereas there is a lot of deposition at the ice margin.”

But the bedrock between Jamestown and Aquidneck Island are different from each other, according to Turenne.

The breaks at Jamestown, for example, are over flat slabs of shale, similar to the break at Bonnet Point, he says, that formed roughly 300 million years ago when the wetland, which is now Narragansett Bay and referred to as the Narragansett Basin, was buried, compacted under tremendous pressure, and transformed into rock.

“If you’ve ever driven through [Route] 138 getting into Jamestown, you go right through the outcrop and notice all the rocks are stratified, and they’re black,” he says, noting the difference between that and the bedrock that lies beneath the Ruggles break, which is a combination of the Narragansett Basin shale and granite rock over 500 million years old that formed when all of the continents were locked into one supercontinent near the South Pole.

The underlying bedrock of Rhode Island was formed during this period when it was a volcanic island arc like Japan is today. “Rodini was the first supercontinent that split apart. Laurentia, which is North America, went north, and Gondwana, which was Africa and South America, went south about 1.2 billion to 500 million years ago,” explains Turenne. “We were part of Africa as a volcanic island arc called Avalonia. All of eastern New England was part of this series of island arcs.”

Future of Surfing in Rhode Island

While processes from the last glaciation took thousands of years, and plate tectonics took several millions or billions of years, to shape Rhode Island’s surf to what it is today, rapid changes in sea levels may change breaks further within a few decades.

Sea level rise is expected to climb up to 8.2 feet over the next century, according to a recent report by the National Oceanic and Atmospheric Administration, due to the rapid melting of the ice cover in Greenland and Antarctica.

Unfortunately, Rhode Island and the rest of New England will experience an additional 1 to 3 feet of sea level rise above the global projection, according to Rhode Island’s Coastal Resources Management Council, due to a variety of factors from increased surface temperatures to changes in the Gulf Stream. This is a significant change in a state that has only experienced 10 inches of sea level rise over the last century.

The consequences of sea level rise are far-reaching, and one area likely affected will be current surf spots.

“Some surf spots change entirely in character over a three-foot tide cycle,” says Caccioppoli, explaining that it’s not uncommon to see surfers leave the water at high tide, especially at Matunuck, where an incoming tide can make the waves deeper and slower.

“Over the long term, [sea level rise] is going to completely change surfing in Rhode Island and everywhere else,” says Klinger. “As the water gets deeper, the waves are going to break differently and closer to shore, and the places we typically line up now won’t be there because the water will be too deep—particularly on those steep bluffs and point breaks.”

Klinger adds that beaches will tend to migrate landward and upward (a process called transgression), if they’re allowed to, changing how those breaks work, and that surfing spots, like wetlands, will drown if the beaches can’t migrate.

“What happens at bluffs like Point Judith and Matunuck is going to be interesting because then it’s an interplay between the rate of sea level rise, the amount of erosion, and what we as people do to prevent that or let it happen,” he says, adding that these processes don’t bode well for surfing in existing spots but may create new breaks in the future. “There’s probably areas we don’t surf today that might be good spots in 100 years.”