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Posted on 06/01/2004 4:21:15 PM PDT by Rebelbase
CAPE CHARLES, Va. - Geologists drilling half a mile below Virginia's Eastern Shore say they have uncovered more signs of a space rock's impact 35 million years ago.
For more than two weeks, scientists drilled around the clock alongside a parking lot across the harbor from Cape Charles. They stopped at 2,700 feet.
From the depths came jumbled, mixed bits of crystalline and melted rock that can be dated, as well as marine deposits, brine and other evidence of an ancient comet or asteroid that slammed into once-shallow waters near the Delmarva Peninsula.
Cape Charles is considered Ground Zero for the resulting 56-mile-wide depression below what's now the Chesapeake Bay. The drilling project marks the first time the geologists explored the inner portion of the inverted-sombrero-shaped crater.
"We expected to see some pretty strange rocks because of the extreme pressure and temperatures that occurred" approximately 35 million years ago, said geologist Greg Gohn, who led the $180,000 project for the U.S. Geological Survey (news - web sites).
Over the past decade, USGS (news - web sites) and Virginia scientists have investigated indications that a 2-mile-wide brilliant ball traveling tens of thousands of miles per hour crashed off the Virginia coast, burrowing thousands of feet and depressing and fracturing the bedrock.
Billions of tons of ocean water vaporized. Millions of tons of debris spewed 30 miles high before collapsing back into the excavation. A train of giant waves inundated the land. The waves then dragged debris as they washed back into the crater, preserving it beneath a blanket of rock and sediment.
It probably took just a few minutes to create the largest crater in the United States and sixth-largest known on the planet, according to computer simulations.
The catastrophe squeezed freshwater from many of the aquifers of southeastern Virginia and filled others with briny water. Its legacy is well-known to residents who try to drill for drinkable groundwater and encounter the saltwater "wedge," pockets of brine nestled in an arc from the lower Eastern Shore to the Hampton Roads-Newport News area.
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.
"We're getting evidence about how hot this thing (was) and what was the energy," said USGS hydrologist David Powars, one of those credited with the crater's discovery.
More clues to the space rock's identity will come from cores taken in the drill's final 280 feet.
A $1.2 million proposal to dig 7,000 feet not far from Cape Charles is before the International Continental Scientific Drilling Program, which would then assist the USGS with funding.
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Before the time of dinosaurs, most of the Midwest was under a great inland sea, with the fairly new Appalachians sticking up as a large island, sort of like Greenland.
The fossils were deposited at that time on the botttom of a sea floor, and later buried under tons of silt and calcium carbonate, becoming beds of shale and limestone containing fossils.
My degree is in geology, and when I was a young woman I did a lot of field work in southern Indiana.
Should be lots of Iridium there if true
Global warming....natures way. It took a 2 second impact. Now add in volcanoes, earthquakes and fluctuations of the universe.
Wonder if this has anyhting to do with the huge caves in this region. The flux from this most have been lateral also.
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Three chunks of the same asteroid, probably, formed all three of these:
http://en.wikipedia.org/wiki/Chesapeake_Bay_impact_crater
http://en.wikipedia.org/wiki/Toms_Canyon_impact_crater
http://en.wikipedia.org/wiki/Popigai_crater
Eocene–Oligocene extinction or Grande Coupure:
http://en.wikipedia.org/wiki/Eocene%E2%80%93Oligocene_extinction_event
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