South Middlesex Times

A Rutgers University-New Brunswick-led research team employing an emerging technique to detect signs of past hurricanes in coastal sediments has found evidence of storms dating back more than 400 years. In doing so, they have confirmed an approach that could give them a better understanding of how the frequency of storms changes when the climate changes.

Reporting in The Journal of Quaternary Science, scientists described finding eight storm deposits forming sediment layers below the surface of New Jersey’s Cheesequake State Park wetlands in Old Bridge, including evidence of a hurricane that occurred as early as 1584 and predates existing instrumental records in the region. In doing so, they have generated a new geological record from these so-called “overwash deposits.”

“These sediment records, which we’ve used to reconstruct past storm histories, allow us to look much further back in time than current instrumentation allows us,” said Kristen Joyse, the study’s lead author who conducted the research between 2019 and 2021 as a doctoral student in the Department of Earth and Planetary Sciences in the Rutgers School of Arts and Sciences.

Sedimentologist Kristen Joyse (at right), conducting research in 2021 as a Rutgers graduate student, extracts sediments from a salt marsh in Cheesequake State Park in New Jersey. Joyse, now of Alluvium, works with Jennifer Walker, another Rutgers doctoral student also on the study who is now at Rowan University.

Scientists seeking patterns of past hurricanes have long relied on records provided by tidal gauges, which are floating sensors installed along coastlines or on ocean platforms that continuously collect data on water height by the minute, hour and day. Researchers also have availed themselves of historical records, such as shipping logs and newspapers, to aid in their analyses.

Such records, however, do not allow researchers to investigate the distant past, said Joyse, a coastal sedimentologist who, after earning her doctoral degree from Rutgers, is now working at the environmental consulting firm Alluvium in Australia. Extending the geological timeline more deeply into the past is necessary for better understanding, she said.

Overwash events—produced when hurricanes create storm surges that carry sand from the beach and dunes to the coastal wetlands—are believed to be another way of finding evidence of past severe storms. To ascertain the accuracy of this record, what scientists refer to as its “preservation potential,” the team compared a portion of the sediment cores they collected with contemporaneous tidal gauge records showing extreme high-water events.

The team located and dated eight cores with records of storm deposits, including one from Hurricane Sandy in 2012. They concluded that four samples showed evidence of storms occurring before the existence of tidal gauges, with the remaining four within modern tidal gauge records. The tidal records used were collected by some of the country’s longest-operating instruments: one located off Sandy Hook's coast (operational since 1932) and another near lower Manhattan known as The Battery (operational since 1920).

The sediment samples made up cores eight feet deep were collected from both peaty and sandy spots and analyzed for grain size, organic content, carbon isotopes and microfossil content. Such characteristics allowed researchers to distinguish sandy storm layers from background wetland sediments. They determined age through radiocarbon dating of woody plant material and concentrations of pollen and heavy metals in sediment.

The oldest deposits included:

- Overwash deposit #5: dated between 1874 and 1923; corresponds with Hurricane of 1938

- Overwash deposit #6: dated between 1773 - 1810; corresponds with Hurricane of 1788

- Overwash deposit #7: dated between 1651 - 1731; corresponds with Hurricane of 1693

- Overwash deposit #8: dated between 1584 - 1658; pre-historic storm (pre-dates all historical/instrumental records)

The four newer deposits mesh with tidal records: Hurricane Sandy (2012); Nor’easter (1953)/Hurricane Donna (1960)/Ash Wednesday Nor’easter (1962); Nor’easter (1950)/Hurricane (1944)/Hurricane (1938); Hurricane (1944)/Hurricane (1938).

The scientists found that while accurately capturing evidence for at least four extreme storm events did not represent a complete record.

Both tidal gauges recorded some extreme water level events not reflected in sediments—the Sandy Hook gauge showed four additional events while New York gauge showed seven additional ones.

“What this tells us is that we know these sediment records can be used to reconstruct past storm histories but not to resolution like tide gauges,” said Robert Kopp co-author on study distinguished professor Department Earth Planetary Sciences director Megalopolitan Coastal Transformation Hub MACH). “These records allow us look much further back time just acknowledge don’t capture every extreme storm makes landfall.”

Findings provide fodder further investigations

“This will allow us make better hypotheses improve understanding how storm frequencies may impacted other climate variables what means future under changing climate,” Joyse said. “It also allows ask new questions: Why do some storms get preserved by sediment record others? How does probability being preserved change time?”

Linda Godfrey associate research professor Department Earth Planetary Sciences Rutgers School Arts Sciences co-authored study

Other scientists included Jennifer Walker Rowan University Margaret Christie McDaniel College D Reide Corbett East Carolina University Timothy Shaw Benjamin Horton Nanyang Technological University Singapore