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Chesapeake Bay Crater Offers Clues To Ancient Cataclysm
Natinal Geographic ^ | 11-13-2001 | Hillary Mayell

Posted on 11/16/2001 1:23:50 PM PST by blam

Chesapeake Bay Crater Offers Clues to Ancient Cataclysm

Hillary Mayell
for National Geographic News
November 13, 2001

About 35 million years ago—the dinosaurs are dead, but the Appalachian Mountains are still covered in tropical rain forests—a rock from space that was more than a mile wide and moving at supersonic speed crashed into the Atlantic Ocean off North America.

Traveling at about 70,000 miles (113,000 kilometers) an hour, the asteroid or comet (bolide) splashed through several hundred feet of water and several thousand feet of mud and sediment.

Drilling for Knowledge

A trailer hauls drilling rods the U.S. Geological Survey used to obtain core samples from a crater near Hampton, Virginia, that was created when a comet or asteroid crashed 35 million years ago.

Billions of tons of ocean water were propelled into the air as high as 30 miles (48 kilometers) and vaporized. Millions of tons of debris and rocks were ejected into the atmosphere. The incident incinerated everything along the East Coast, triggered gigantic tsunamis, and decimated marine life in the surrounding area.

For millions of years the crater lay buried in the southern part of the Chesapeake Bay and surrounding peninsulas, more than a thousand feet (300 meters) beneath sand, silt, and clay. Scientists discovered it in 1983 and have been studying it ever since.

For the past two summers, researchers have been extracting core samples from deep inside the crater. The core material is beginning to provide the answers to a lot of questions about the crater and its effects in the region.

"We're finding things that are giving us an idea of the heat and power at the time of impact—partially melted algae fossils, completely shattered rocks, lots of basin fragments, fractured and tilted seabeds," said David Powars, a hydrologist at the U.S. Geological Survey (USGS).

Powars and C. Wylie Poag, a USGS colleague, presented some of the results of their research earlier this month in Boston at the annual meeting of the Geological Society of America.

"It's pretty exciting," Powars said. "In every direction there's new data. Wylie and I are like two kids with candy."

Unusual Geologic Conditions

The new findings offer greater insight into geological and hydrological conditions of the Chesapeake area and eastern Virginia that have puzzled scientists for more than a century.

The land is sinking, erosion patterns are unusual, and earthquakes have occurred in this region not known for earthquakes. The groundwater in some areas of the region is salty, and three rivers in the area have abrupt—and highly unusual—90-degree turns.

One thing the core samples show, according to Powars, is that the roughly circular crater is much bigger and deeper than originally thought.

When it hit, the asteroid or comet "fractured the crystalline bedrock below to at least a depth of 7 miles (11 kilometers) and a width of 85 miles (137 kilometers). This was a big hit," he said.

Earlier estimates had suggested the crater was about a mile deep (1.3 kilometers) and 53 miles (85 kilometers) wide.

The impact of the bolide disturbed the normal layering of sediment, rocks, and aquifers, and water from many of the wells in the region is salty or brackish.

Utility companies in eastern Virginia are funding some of Powars' work because the findings have a direct bearing on the search for fresh ground water needed to supply growing populations in the region.

Linked With Extinction?

Scientists have long suspected that the heat from the impact incinerated every living thing within hundreds of miles. The core drilling has revealed a zone of silt that is devoid of signs of indigenous life, lending credence to that hypothesis, said Poag.

Poag believes the impact could have influenced an extinction that occurred about 33 million years ago.

The early Oligocene extinction dramatically affected land mammals. Forest dwellers declined as forested habitat became less abundant, while hoofed animals flourished as a result of increasing temperate grasslands. A number of predators also became extinct at this time, mainly because of changes in vegetation.

The asteroid or comet that struck the area that later became the Chesapeake Bay may be evidence of a 2 million-year-long comet shower that scientists think may have occurred between 36 and 34 million years ago.

An even bigger crater in Popigai, northern Siberia, was created at about the same time. Scientists also have found traces of helium 3, an isotope associated with extraterrestrial objects, in sediment layers in Massignano, Italy, and other places dating to 35 million years ago.

"Global paleo-temperatures during the early Eocene show the world was getting cooler," said Poag. "Around 35 million years ago, at the end of the Eocene, there was a warm pulse, and for a short period of time the Earth warmed. Then beginning at around 34 million years ago the Earth cooled very rapidly. At 33.4 million years ago there was a major extinction event."

The aftermath of the bolide collision, Poag said, would have been prolonged darkness and acid rain caused by the fallout of rocks, dust, and particles that were blasted into the atmosphere, along with the residual effects of raging wildfires.

These conditions, he suggests, would cause the abrupt cooling of Earth, leading to the extinction that eventually occurred.


TOPICS: Culture/Society; News/Current Events
KEYWORDS: archaeology; catastrophism; chesapeakebay; ggg; godsgravesglyphs; history
Don't forget the Leonid shower coming up this weekend. It is being covered on other threads.
1 posted on 11/16/2001 1:23:50 PM PST by blam
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To: blam
good posting,thanks.
2 posted on 11/16/2001 1:23:51 PM PST by green team 1999
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To: RightWhale; sawsalimb; JudyB1938
Bump.
3 posted on 11/16/2001 1:23:53 PM PST by blam
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To: blam
Excellent article. Thanks!

When I first moved to Maryland, there was a short series of essentially "unexplained" Richter 2-3 earthquakes in eastern Howard County. The geologists cited a fault system that runs through Howard County and northern Baltimore County. I wonder if the fault could be related to the southern Chesapeake Bay impact site. Probably not, but a possibility, I guess.

4 posted on 11/16/2001 1:23:55 PM PST by cogitator
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To: blam
Thanks-had never heard of this one. Also,regarding your earlier thread on meteor impacts causing the fall of civilizations,I have no trouble at all finding this plausible. An impact wouldn't even have to be that big(in relative terms) to wipe out a culture that was based on human labor and animal transport. Evacuation would have been undreamed of,and even if you survived the initial impact,if the devastated area was more than a few hundred miles in diameter,scraping together enough food to sustain yourself and finding some way to transport it to another location would be next to impossible for more than a tiny number of people.
5 posted on 11/16/2001 1:23:55 PM PST by sawsalimb
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To: blam
Cable (A&E or TNT) will be showing a program about animal life during the Tertiary Era, the Age of Mammals, which followed the Dinosaurs. It is going to concentrate on the first half of the Era. the up through the Oligocene period referred to in this story.

The animals of this time look stranger than the Dinos, because we have been shown a lot about the great reptiles. The predators at that time were called creodonts, now totally extinct except for their descendants the whales. They looks something like current carnivores, since they filled the same niches, but are not related. The carnivores existed in hiding, looking rather like a cross between foxes and coyotes. All current carnivores descended from them.

The largest land animal that has lived since the Dinosaurs was a really weird animal called the 'Beast of Baluchistan', discovered in that province which neighbors afghanistan. It has no living relatives. All in all a really strange period, much less familiar than the time of the Dinosaurs, despite being closer in time, and including animals much more closely related to our current fauna.

6 posted on 11/16/2001 1:23:56 PM PST by Lucius Cornelius Sulla
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To: blam
BUMP
7 posted on 11/16/2001 1:23:56 PM PST by Aurelius
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To: cogitator
Wild speculation on my part-I live in South Central Texas,and a few mild earthquakes occur south of San Antonio from time to time. There has also been speculation that the western half of the Gulf of Mexico(the Texas coastline and the Yucatan Peninsula)is actually the remnants of a big meteor strike. Wonder if there's a connection.
8 posted on 11/16/2001 1:23:56 PM PST by sawsalimb
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To: blam
Interesting article.

About 35 million years ago—the dinosaurs are dead, but the Appalachian Mountains are still covered in tropical rain forests—a rock from space that was more than a mile wide and moving at supersonic speed crashed into the Atlantic Ocean off North America.

Supersonic? Now there's an understatement. We're almost certainly talking about an impact speed in the tens of miles per second compared to around 1,100 feet per second for the speed of sound.

Presumably what the writer meant by 'supersonic' was "really, really fast..."

9 posted on 11/16/2001 1:23:57 PM PST by Interesting Times
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To: sawsalimb
There has also been speculation that the western half of the Gulf of Mexico(the Texas coastline and the Yucatan Peninsula)is actually the remnants of a big meteor strike.

The meteor strike 66 million years ago that kilt off the dinosaurs was in the vicinity of the Yucatan Peninsula.

Supposedly kicked up stuff as far as the Pacific Northwest.

10 posted on 11/16/2001 1:23:59 PM PST by DuncanWaring
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To: Interesting Times
Supersonic? Now there's an understatement.

The quoted "70,000 miles per hour" works out to roughly Mach 100.

11 posted on 11/16/2001 1:23:59 PM PST by DuncanWaring
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To: sawsalimb
There has also been speculation that the western half of the Gulf of Mexico(the Texas coastline and the Yucatan Peninsula)is actually the remnants of a big meteor strike. Wonder if there's a connection."

Don't know about the connection but, the Chixlub (dino killer 65 million years ago) crashed just north of the Yuchatan in the Gulf of Mexico.

12 posted on 11/16/2001 1:23:59 PM PST by blam
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To: blam
Our local paper did a seven part series on this. Here is the link. Enjoy. Click here
13 posted on 11/16/2001 1:24:02 PM PST by csvset
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To: blam
Good post!
14 posted on 11/16/2001 1:24:11 PM PST by aculeus
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To: csvset
Good link. Thanks.
15 posted on 11/16/2001 1:26:57 PM PST by blam
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To: blam

16 posted on 11/16/2001 2:40:26 PM PST by blam
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To: blam

17 posted on 11/16/2001 2:42:15 PM PST by blam
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To: blam

18 posted on 11/16/2001 2:44:44 PM PST by blam
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To: blam

19 posted on 11/16/2001 2:46:56 PM PST by blam
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To: blam

20 posted on 11/16/2001 2:48:33 PM PST by blam
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To: blam

21 posted on 11/16/2001 2:50:01 PM PST by blam
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Just adding this to the GGG catalog, not sending a general distribution.
Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
The GGG Digest
-- Gods, Graves, Glyphs (alpha order)

22 posted on 05/03/2005 10:00:42 AM PDT by SunkenCiv (FR profiled updated Monday, April 11, 2005. Fewer graphics, faster loading.)
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