U.S. Water News Online
CHERITON, Va. -- About a mile off U.S. 13, amid fields of
green-and-yellow soybeans, geologists are closing in on an ancient
Recently, an international team of scientists used an 80-foot-tall
drill rig to pull out yet another 10-foot core of clay and silt that
sits atop a 53-mile-wide crater buried below the Chesapeake Bay.
Drilling with the fire-engine-red rig fitted with
diamond-encrusted bits whirring up to 2,000 rpm will continue for the
next three months at the Buryn family farm in the Eyreville area
northwest of Cheriton. The farm is just off-center from where
geologists say a 2-mile-wide fiery space rock exploded more than 35
million years ago, creating an inverted sombrero-shaped crater that
quickly filled with tons of water and debris.
The $1.3 million Eyreville project aims to dig 7,200 feet -- more
than twice the depth of previous crater drills at more than a dozen
sites around Tidewater Virginia and the Eastern Shore.
Since Sept. 14, the team has drilled to a depth of 1,433 feet.
"We're moving along really well," said Greg Gohn, the U.S.
Geological Survey scientist leading the project. "We're hoping to
break through at any second" into the layer of rubble just above the
Four-dozen scientists are working with technicians at the site in
12-hour shifts around the clock to take cores in 5- or 10-foot
segments. They expect to reach the crater floor and unearth traces of
the space rock. They also may find water trapped in the crater's
depths by the impact's aftermath and perhaps descendants of the
original microbes that floated in the waters off Virginia millions of
years ago, said microbiologist Charles Cockell of Open University in
the United Kingdom.
The Chesapeake Bay impact crater is the largest in the United
States and the sixth-largest in the world. As deep as the Grand
Canyon, it sits below about 1,000 feet of rubble and sediment beneath
the lower part of the Chesapeake Bay, its surrounding peninsulas and
the inner continental shelf of the Atlantic Ocean.
"The cores are really telling us the story of this crater," said
David Powars of the USGS, one of the crater's co-discoverers.
Geologists hope the drill will tell them more about the effect the
prehistoric impact had on the seabed and provide better estimates of
the space rock's speed, size and energy as it slammed into the sea
In the rubble brought up by the drilling, scientists hope to find
clues about the Earth's primeval climate and where thirsty Tidewater
residents can find drinkable water.
Geological research off the coast of New Jersey and in Virginia,
begun in 1983, led to the crater's discovery a decade later. Drilling
and further study of seismic data narrowed the location in the
Chesapeake Bay and identified Cape Charles as "ground zero."
The impact sent a shock wave about 7 miles underground, melted
rock, spewed debris, briefly exposed the seafloor and vaporized
water. The deep gouge was then covered beneath a thick blanket of
debris, rock and sediment and water. As this crater settled, it set
the stage for Virginia's baffling coastal groundwater system, with
its pockets of salty groundwater.
Its legacy is well-known to residents who try to drill for
drinkable water and encounter the saltwater "wedge," pockets of
brackish groundwater nestled in an arc from the lower Eastern Shore
to the Hampton Roads-Newport News area.
The USGS has spearheaded the Chesapeake Bay impact-crater
research. The agency is now partnering on the Eyreville drill with
the International Continental Scientific Drilling Program, which is
putting $900,000 toward the project.
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