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| Conor Veeneman '09
and Joel LaBella, facilities manager for the Earth and Environmental
Sciences Department, prepare to take a core sample of Block Island's Great Salt Pond.
Sediment samples may reveal that Block Island was not formed by the
conjunction of two smaller islands more than 6,000 years ago, which is the
current belief. |
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| Posted 08.06.08 |
Scientists, Students Get to the Core of Block Island
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More than 2,500 years ago, Native Americans settled on an area of land
located about 13 miles off the coast of Rhode Island. They named the area
“little island” or “little god place.” Much later, in 1614, it was charted
by Dutch navigator Adrian Block and became known by colonists as the name it
retains today: Block Island.
Now a popular tourist destination, the island is full of geological
mysteries. But a group of Wesleyan-affiliated researchers have spent the
summer studying the geologic and environmental history of the island. They
are particularly interested in the environmental impact of humans, tracing a
time line from the early Native Americans inhabitants to colonial settlers
to present day.
 “Our
long term goal is to investigate the history of the island back to the time
of the last ice age – approximately 20,000 years ago – when the glaciers
retreated from the island,” explains Johan Varekamp, the Harold T. Stearns
Professor of Earth Science (pictured in orange at left). “When did large
lakes form there? Which drained and when did the sea inundated the former
land with the modern island as its remnant? What associated changes in land
use – cutting of forest, beginning of agriculture, first with corn and
cattle – led to extensive deforestation? There are many questions to be
answered.”
The island research team includes Varekamp; his wife Ellen Thomas, who is a
research professor of earth and environmental science at Wesleyan and a
senior research scientist at the Center for the Study of Global Change at
Yale University, as well as students from Wesleyan, Macalester College, Bryn
Mawr College, Smith College, and The State University of New York at New
Paltz. The study and student participation was made possible by a grant from
the W.M. Keck Foundation
A majority of their fieldwork was conducted in various water basins on the
island, most prominently the massive Great Salt Pond. In July, the group
used 40-foot-long aluminum pipes to core – or extract – layers of sediment
from three locations.
Nowadays, the Great Salt Pond is true to its name. It’s currently salty
water, a close concoction of regular seawater. But during human’s
colonization of the island, the pond went through bouts of being a fresh
water basin.
“The initial core records suggest that most of the time the Great Salt Pond
was indeed salty, so with this study, we hope to reconstruct these periods
of fresh or brackish water versus the open periods with salt water,”
Varekamp says. “The pond was totally closed off from the sea for some time;
the story is that the Native Americans opened a connection with the sea, but
that rapidly filled-in with sand. Once the colonials arrived around 1661,
they opened it up again. If the spot is not dredged regularly, it will fill
in with sand.”
The core samples also reveal eutrophication – or increase in chemical
nutrients – in the pond’s ecosystem. By examining the sediment, Varekamp
notices significant color changes to the marine soils. Sediments dating to
early in the last century are gray to olive-gray, which shows a natural
process in the pond. The sediment at top of the core samples, which are from
more recent times, are solid black – indicating a dramatic, human-influenced
change to the pond’s ecosystem during the last 100 years or so.
The three Wesleyan students, Sarah Gillig ‘09, Conor Veeneman ‘09 and Emma
Kravet ’09, assisted with multiple aspects of the study such as collecting
foraminifera data (saline versus fresh waters, enclosed basin versus open
marine bay), mercury analyses, and selecting shells for radiocarbon dating.
Gillig, a Hughes Fellow, analyzed foraminifera in attempts to examine the
popular idea that Block Island was formed by the conjunction of two smaller
islands more than 6,000 years ago.
“We have not found any evidence for that in our cores yet, but it will be
another two months before we have our radiocarbon dates back from the lab
with ages,” Varekamp says. “The problem is, our cores may not go back 6,000
years!”
The group received help from local residents, including Walter Filkins III
’70, who allowed the team to use his boat.
“Our research team was fun and motivated, but thanks to the locals, our time
on the island was efficient, successful, and relatively painless,” says
earth and environmental sciences major Veeneman. “The consistent and
overwhelming support of the local islanders lending boats and supplies,
providing helpful insight of the island culture and history was
indispensable to our sample collection and overall research progress.”
Varekamp, who specializes in mercury studies, also cored the island’s water
basins for any signs of pollution. Because Block Island is a remote
environment, any mercury found on the island is deposited from the air and
originated elsewhere. In a previous study, he found that there was about
fifty percent less mercury pollution on the island than found in central and
eastern Connecticut.
The researchers are currently finishing basic sample processing at Wesleyan.
In late August, they will send their “samples of interest” to external labs
to determine mercury levels, carbon/nitrogen ratios, radiocarbon dates and
foraminifera species concentrations.
They will present their data and an island evolution model during the North
Eastern Estuarine Research Society on Block Island in October.
Their research was featured in the
Block Island Times July 14.
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By Olivia Bartlett, The Wesleyan Connection
editor. Photos contributed by Joop Varekamp. |
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