[meteorite-list] Project Aims to Drill Into Chesapeake Bay Impact Crater

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Aug 22 12:31:37 2005
Message-ID: <200508221611.j7MGBrd05934_at_zagami.jpl.nasa.gov>

http://home.hamptonroads.com/stories/story.cfm?story=90953&ran=18092

Project aims to drill into impact crater on Eastern Shore
By DIANE TENNANT
The Virginian-Pilot
August 22, 2005

An international project involving 13 countries will drill more than a
mile deep into an ancient impact crater on the Eastern Shore, looking
for clues to prehistoric climate, modern-day water problems and the
beginnings of life on Earth and Mars.

In three weeks, the first samples of rock and sediment should start
coming out of a hole on a farm just north of Cape Charles. From them,
scientists hope to learn about Earth's climate history, what really
happens when an asteroid or comet collides with a planet, how life
survives in the presence of tsunamis, massive fires and shock and, of
more local concern, why groundwater in Hampton Roads is so salty.

"We hope to drill entirely through the crater and into its floor," said
Greg Gohn of the U.S. Geological Survey, one of four principal
investigators for the project. 'None of us will probably ever drill a
7,000-foot hole again."

The USGS has drilled eight holes into the outer trough and edges of the
crater, which is about 56 miles wide and at least a mile deep. Core
samples - long tubes of rock and dirt - have been taken from sites in
Hampton, Newport News, Mat hews County, Gloucester and several places on
the Eastern Shore. But the deepest of those was only 2,699 feet, less
than half of the ambitious attempt to go 7,218 feet that will begin in
early September.

'We'll be crossing bridges that nobody's crossed," said USGS scientist
David Powars, one of the first to suspect an impact crater lay under the
Chesapeake Bay. Powars and other scientists, trying to figure out why
some aquifers were salty and why older fossils could be found l ying on
top of younger ones, announced the existence of the crater in 1994. For
decades prior, such strange evidence had been considered the results of
poor sampling and poorer science, rather than the ground truth of a
cosmic collision.

The Chesapeake Bay impact crater is the sixth -largest in the world. Its
center is under Cape Charles, and it is concealed under layers of
sediment that have filled the gigantic hole in the 35 million years
since it was blasted out by an object from outer space. Because it is
buried, it is one of the best preserved craters in the world.

"This is going to be so exciting to see what comes out of this hole,"
Powars said, and to those who know the excitable Powars, those are words
to live by.

The $1.3 million project is funded by the USGS and the International
Continental Scientific Drilling Program. The program is a consortium of
science agencies in 13 countries, including China, Canada, Germany and
South Africa. In the United States, the National Science Foundation is
the funding partner.

The program focuses on globally significant sites, such as the Chicxulub
crater (possible cause of dinosaur extinction) on the Yucatan Peninsula,
the San Andreas earthquake fault, plate tectonics in Crete and volcanoes
in Hawaii.

In addition, 118 scientists have made 44 proposals to use core samples;
that research will be funded separately from the drilling budget.

The drilling rig is expected to arrive on Sept. 9 and set up in the
midst of soybean fields at Eyreville, a farm that was settled by
Englishmen in the early 1600s. But the original occupants may have been
there much longer.

British scientist Charles Cockell will lead the search for microbes that
could have survived the impact and still be colonizing the rocks deep in
the earth. Such extremophiles, as they are called for their ability to
live in extreme environments, could have quietly taken up residence in
the spaces that formed in the rock when it was blasted out of the hole,
then fell or washed back into the crater.

If microbes are found, Cockell will attempt to grow some in a lab, and
Penn State microbiologist Jennifer Macalady will examine their DNA.
Large amounts of iron in water samples taken from the crater may
indicate microbes that can use electrons from iron for energy.

"The meek shall inherit the Earth, that's what I always say," Cockell
said on a recent trip to the Eyreville site. "That's the thing about
microbes. They don't just survive, they find new opportunities.
Catastrophes create new opportunities for life."

Crater scientists, including Powars, presented information in July at
the Lunar and Planetary Institute's conference about Martian impact
craters. The shape of the Chesapeake Bay crater - a central peak
surrounded by a deep ring, which is then surrounded by a wide, more
shallow brim - could be a useful comparison to craters on the Red
Planet. The Bay crater was formed by an object that landed in a shallow
sea. The wet sediments of the sea floor broke off in chunks and slumped
toward the deep inner ring, making the crater much larger than it might
have been had the object hit land.

Similar-looking impact craters on Mars could mean they also formed in
water or in comparable sediments, the researchers wrote. And there's more:

"These impact craters were possibly the source of life, and that's not
just whistling 'Dixie,'" Powars said. "A crater with hydrothermal
activity on other planets could be the place where life begins."

Other science teams will look at how the crater formed and what physical
properties it has. In the melted rock deep inside, traces of the object
that made the crater may exist as chemical signatures of elements rare
in Earth's crust. The immediate effects of such a large impact also will
be examined - tsunamis that could have hit Europe and bounced back,
wildfires that set the entire East Coast ablaze, melted sand that formed
glass beads to float thousands of miles in the wind.

Modelers will take information from the core hole and project what might
happen if another space rock were to hit Earth today. In the younger
sediment layers at the top of the crater, geologists hope to find
information on historic climate changes that affected sea level and ice
sheets.

Of local interest, hydrologists will look at how the crater disrupted
freshwater aquifers that supply drinking water in Hampton Roads. Samples
from other holes have produced water saltier than the sea, and
scientists hope to gain understanding on how the crater impedes the flow
of water.

Once drilling begins, it will continue 24 hours a day for three months.
During that time, farmer Roger Buyrn will likely be inconvenienced by
traffic on his narrow farm lane, drilling lights and noise, and
publicity from international media. He has no regrets.

"My father had a saying: 'It's a very good day when you learn
something,'" Buyrn said. "He also would say, 'Try to learn something
every day.' How would you say no when there's an opportunity to learn so
much?"
Received on Mon 22 Aug 2005 12:11:49 PM PDT