[meteorite-list] Chesapeake Bay Impact Crater (Part 2 of 7)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:14 2004
Message-ID: <200106261705.KAA21713_at_zagami.jpl.nasa.gov>

http://www.pilotonline.com/special/meteor/part2.html

Cryptic clues from the past
By DIANE TENNANT
The Virginian-Pilot
June 25, 2001

Part 2 of 7

Rocks from heaven have bedeviled Earthlings for centuries.

The main problem, of course, was that folks thought rocks should remain on
the ground and not go jaunting about through the air.

To explain the inexplicable, some suggested that the rocks were vacuumed up
by waterspouts, then dropped by thunderstorms. Others linked them to the
devil.

Ernst Chladni, a German physicist, proposed in 1794 that they fell from
space, prompting a colleague to complain that the theory made him feel as
though he had been hit in the head by one of those rocks, and another to
accuse Chladni of bringing evil to a moral world.

The debate raged on, even as rocks continued to fall around the planet in a
sunny-with-occasional-showers sort of pattern. A few fell on Weston, Conn.,
in 1807 and two brave geologists from Yale identified them as coming from
space. Thomas Jefferson joined in the ridicule, reportedly writing that he
``would rather believe that those two Yankee professors would lie than to
believe that stones fell from heaven.''

Only scant miles from his White House in Washington, the sixth-largest
impact crater in the world silently continued altering the landscape, as it
still does after 35 million years.

The Exmore drilling took months in 1986, as the U.S. Geological Survey
pushed forward with its mapping and the state kept looking for water.
Misfortune plagued the project: drill rods didn't fit together, the drill
was pushed almost twice as deep as it was meant to go, the stored cores were
attacked by fungus in a farm shed.

``They were yelling at me every day that it was my neck on the line, all the
rods were going to get lost in the hole, and the drill bits, it was all
going to be me,'' David Powars says. ``Wiped me out, all this stuff. But I
could not figure out what the heck we were in, where we were, what had
happened, and I can remember everybody laughing so hard when I said, `Maybe
it's an impact crater.' ''

The idea hit Powars like a rock from heaven.

Only one person reportedly has ever been hit by a meteorite. In 1954, Annie
Hodges of Sylacauga, Ala., was struck by an 8-pound stone that came through
the roof of her house, smashed the radio and bounced into her leg. This
event, according to impact-crater expert John S. Lewis, is the only case
verified by both scientists and a medical doctor. However, in his book
``Rain of Iron and Ice,'' Lewis notes many records of uncertified impacts
that killed, injured or just alarmed people from biblical times to the
present, leading him to his own wry conclusion that, ``No one in recorded
history has ever been killed by a meteorite in the presence of a
meteoriticist and a medical doctor.''

These historical accounts mention the Bible's Joshua, Charlemagne, various
monks and the Chinese army. One of the most recent was in Peekskill, N.Y.,
on a Friday night in 1992. Because so many people were outside in high
school football stadiums, thousands saw a fireball flash across Ohio,
Pennsylvania and Virginia. The 27-pound rock landed on the trunk of a red
Chevy Malibu and fell to the sidewalk where it lay, warm to the touch, in
front of the car's astonished owner. All of these celestial objects made
quite an impact on the witnesses and victims.

So when Powars was hit with the crater idea, it, too, left a lasting
impression.

The core was in front of him, and it wasn't wrong. He didn't know why it
wasn't wrong, but he knew it had not been contaminated by bad sampling. He
sent a section to a colleague for fossil dating. C. Wylie Poag, a USGS
senior research scientist in Woods Hole, Mass., wrote back that fossils from
different geologic ages were mixed in the sample, older above younger, or
side by side. Powars began to read up on the Mattaponi Formation and compare
John Cederstrom's descriptions of the layer -- his lithology -- with his
own.

Cederstrom thought the Mattaponi covered the entire state but was unable to
prove it. Powars plotted his points and drew his own map of how widespread
the Mattaponi might be. His colleagues were not amused. They argued that
Powars was using flawed data to produce more flawed data. But he couldn't
stop wondering what lay under the Chesapeake Bay.

Ordered to move on to other projects in his day job, he labored on the
puzzle through nights, weekends and vacations. His reference books,
logbooks, drawings, maps and overlays covered the floor and tables of his
home office. He was convinced that the Mattaponi was not a normal formation
laid down by erosion but a heap of debris possibly caused by an undersea
avalanche. He began to call it a ``boulder bed,'' and he believed it covered
nearly 2,000 square miles of subsurface Virginia. But why?

Late one night, after his wife had gone to bed, Powars straightened his
aching back and said aloud, ``I wonder if anything's going to come of all
this work?''

The USGS wanted to drill a core hole at Reedville on the Northern Neck, to
keep going in a straight line on its original mission of defining
sedimentary beds in the coastal plain. Powars badly wanted another core from
the Eastern Shore.

The USGS refused, but Powars has never been one to take no for an answer.
``I don't mind being out on a limb,'' Powars says. ``I like working the
puzzle. I'm the first one to admit I don't understand it, but I'm a good one
to throw in there that you don't understand it, either. Here's this data
that suggests this or this: How do we prove one way or the other that this
is what it really means?''

He waves his arms. The exercise helps him to think out loud, which helps him
to compare information, reach new conclusions and think of completely new
questions to research. Sentences do not seem to end when Powars talks. They
go on and on and on until they merge with an unrelated thought and angle off
like the James River did when it turned north and east, headed for the
Eastern Shore.

Powars wanted another core hole there to test his theory that the boulder
bed extended south of Exmore. Drillings in conjunction with the State Water
Control Board at Fentress, the Dismal Swamp and to the north at Jenkins
Bridge had produced normal layering of the sedimentary beds.

``With Fentress here and Exmore there, we knew that from here to there was a
world of difference,'' Powars says. ``Everybody thought we had a really big
fault here, a tectonic fault.''

Scott Bruce of the State Water Control Board needed a research station on
the Eastern Shore where he could sink wells into every known aquifer.
Through such stations, the state could keep tabs on whether well pumping was
depleting or contaminating the aquifers, and issue permits for pumping based
on the information.

Bruce favored the southern end of the Eastern Shore because he had no
research wells there, and his support -- moral and financial -- proved
critical. The USGS and Water Control Board joined forces at Kiptopeke, a
wildlife refuge on the tip of land where the Chesapeake Bay yawns into the
open Atlantic.

It was exactly what Powars needed.

He already had well data and lithic descriptions -- detailed notes on color,
texture, grain size, fossils -- from the 1800s, from the 1920s and from
Cederstrom's work in the '40s. Plus, he had a big advantage over early
geologists: he had cores. Those cores -- from Exmore, from Newport News and
from Kiptopeke -- were showing him a widespread layer of boulders and
debris. His plotting maps began to show a wall, a sudden dropoff in rocky
layers. He needed to test his theory, needed a sort of ultrasound picture of
what lay deep under his feet, and serendipity intervened.

Bruce had been working the Kiptopeke core hole when he saw a line of seismic
survey trucks rumble up the Eastern Shore. He ran the drivers down, chatted
them up and learned that they were shooting sound waves into the ground and
capturing the reflections for oil companies seeking new reservoirs of
petroleum and natural gas. Bruce took down names and numbers.

Powars began working the telephone. Reach Diane Tennant at 446-2478 or
dianet_at_pilotonline.com
Received on Tue 26 Jun 2001 01:05:31 PM PDT