[meteorite-list] Studying The Chesapeake Bay Crater

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:08:24 2004
Message-ID: <200209111642.JAA03565_at_zagami.jpl.nasa.gov>

http://www.cbsnews.com/stories/2002/09/10/tech/main521475.shtml

Studying A Monstrous Meteor
Associated Press
GLOUCESTER, Vt., Sept. 10, 2002

(AP) Scientists are in Gloucester and Mathews counties to conduct the latest
phase of a study of how a collision with a huge meteor 35 million years ago
affected the Chesapeake Bay region.

The impact left a crater about 56 miles wide and a mile deep. Chunks of
debris were blown into the air. Some of it settled back into the crater in a
jumble and the rest formed two concentric, uneven ridges.

The jumble of sediment and rocks displaced the aquifers, the underground
water supplies that now provide water for thousands of people and businesses
in southeastern Virginia. Much of the water near the crater is too salty to
drink.

The outer rim is a zone, not a clearly defined circle, said Scott Bruce, a
groundwater geologist with the state Department of Environmental Quality. He
said that if scientists can locate the outer rim more precisely, it should
be easier to go outside the rim to where the geologic formations and
aquifers have not been disturbed and find fresh water underground.

Gloucester and Mathews are prime study areas because they lie near the outer
rim. The inner rim is in the bay, several miles off the shoreline.

Last year, researchers from the U.S. Geological Survey and the DEQ bored two
deep holes in Mathews and extracted core samples to analyze the materials
that form the rim.

The data that will be collected in the next few weeks, and analyzed over
coming months, will provide more information about the shape of the rim.
Rufus Catchings, a seismologist with the USGS, described the research as
"ultrasound of the underground."

Workers will put out flag markers along roads in five areas. The routes will
be one to two miles long. After the mapping, they will bore a 10-inch hole
every 15 feet or so along each route.

Next week, the scientists will begin dropping a "geophone," a device to
record energy waves, into the holes. Then they will fire a noisemaking
projectile into the ground. A computer will analyze the resulting energy
waves, which will reveal the density of surrounding soil - the jumbled
pieces of the outer rim.

Bruce said the noise will sound like a thump and won't be loud enough to
scare people or animals.
Received on Wed 11 Sep 2002 12:42:36 PM PDT