I was watching the History Channel today and learned that 35 million years ago an asteroid, about a mile long, hit the area where the Chesapeake Bay is today. Fairfax County was a tropical rainforest.

Chesapeake Bay impact crater
http://en.wikipedia.org/wiki/Chesapeake_Bay_impact_crater

The Chesapeake Bay impact crater was formed by a bolide that impacted the eastern shore of North America about 35 million years ago, in the late Eocene epoch. It is one of the best-preserved "wet-target" or marine impact craters, and the largest known impact crater in the U.S. Continued slumping of sediments over the rubble of the crater has helped shape the Chesapeake Bay.

Formation and aftermath

During the warm, late Eocene, sea levels were high, and the Tidewater region of Virginia lay in the coastal shallows. The shore of eastern North America, about where Richmond, Virginia, is today, was covered with dense tropical rainforest, and the waters of the gently sloping continental shelf were rich with marine life that was depositing dense layers of lime from their microscopic shells.

The bolide impacted at a speed of many kilometers per second, punching a deep hole through the sediments and into the granite continental basement rock. The bolide itself was completely vaporised, with the basement rock being fractured to depths of 8 km (5.0 mi), and a peak ring being raised around it. The deep crater, 38 km (24 mi) across, is surrounded by a flat-floored terrace-like ring trough with an outer edge of collapsed blocks forming ring faults. The entire circular crater is about 85 km (53 mi) in diameter and 1.3 km (0.81 mi) deep, an area twice the size of Rhode Island, and nearly as deep as the Grand Canyon. Numerical modeling techniques by Collins, et al. indicate that the post-impact diameter was likely to have been 40 km (25 mi), rather than the observed 85 km (53 mi).[2]

The surrounding region suffered massive devastation. USGS scientist David Powars, one of the impact crater's discoverers, has described the immediate aftermath: "Within minutes, millions of tons of water, sediment, and shattered rock were cast high into the atmosphere for hundreds of miles along the East Coast." An enormous seismic tsunami engulfed the land and possibly even overtopped the Blue Ridge Mountains[citation needed]. The sedimentary walls of the crater progressively slumped in, widened the crater, and formed a layer of huge blocks on the floor of the ring-like trough. The slump blocks were then covered with the rubble or breccia. The entire bolide event, from initial impact to the termination of breccia deposition, lasted only a few hours or days. In the perspective of geological time, the 1.2 km (0.75 mi) breccia is an instantaneous deposit. The crater was then buried by additional sedimentary beds that have accumulated during the 35 million years following the impact.

Another, smaller bolide impact site, the Toms Canyon impact crater, lies about 322 km (200 mi) to the northeast, on the continental shelf off the coast of New Jersey. It is possible that this crater, having been dated to the late Eocene also, may have been formed in the same impact event as the Chesapeake Bay crater.
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Fairfax has felt like a tropical rainforest for the last three weeks

I didn't realize Elizabeth Schultz was that old. I had her pegged into the 75-80 million year range. Good to know.

Haaaaaa Wrote:
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> I didn't realize Elizabeth Schultz was that old. I
> had her pegged into the 75-80 million year range.
> Good to know.
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Yes, saw a great presentation a few years ago from one of the NASA scientists doing the field work on it. Guy knew his stuff but was a little too much on the doom and gloom of the next object to hit Earth.

Tray von Martin Wrote:
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> Yes, saw a great presentation a few years ago from
> one of the NASA scientists doing the field work on
> it. Guy knew his stuff but was a little too much
> on the doom and gloom of the next object to hit
> Earth.

The one that hit VA was only a mile long compared to the one that hit South America that was 6 miles long. Ours did little damage to the Earth as a whole.

Libs were already blaming Bush for global warming 35,000,000 years ago.

That impact spawned the trolls who thrive in such numbers on this website to this day...

The impact did have one lasting historic impact - well water. During the settling of area, wells dug in the vicinity of the Chesapeake often came up salty, even miles from salt water. This presented problems for early settlers who resorted to using surface water. Now we know why - the whole geologic understructure in the area had been severely disrupted. Pretty cool solution to an old mystery.



Edited 2 time(s). Last edit at 07/06/2013 11:13PM by abelard.

Mr. Spock Wrote:
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> Another, smaller bolide impact site, the Toms
> Canyon impact crater, lies about 322 km (200 mi)
> to the northeast, on the continental shelf off the
> coast of New Jersey. It is possible that this
> crater, having been dated to the late Eocene also,
> may have been formed in the same impact event as
> the Chesapeake Bay crater.


You forgot to mention the micro-bolide impact site of Manassas.

jJEk3 Wrote:
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> You forgot to mention the micro-bolide impact site
> of Manassas.

I wasn't aware there was one.

How was the crater found?
http://meteor.pwnet.org/impact_event/impact_crater.htm

Identifying the impact crater has been a puzzle that has consumed thousands of hours of research. Since the crater is hidden from sight, tangled clues began to emerge during a search for water for thirsty Virginians, which slowly led to this unexpected discovery far out in the Chesapeake Bay.

Understanding the impact crater requires understanding the geology of Virginia. Virginia's Coastal Plain is a slopping series of sedimentary beds of sands and clays that were laid down in orderly fashion over millions of years. This subterranean layer cake has been studied for the past 200 years.

Within these layers lie aquifers. Nine aquifers have been identified and tapped for water for hundreds of years. It is from these aquifers that the freshwater needs of Virginians have been quenched.

After World War II, Virginia's growing population demanded more freshwater. Existing reservoirs and wells were not predicted to meet the growing demands. During the 1950s and 1960s, the state of Virginia began to sink test wells to determine the location and extent of the aquifers in the Coastal Plain.

T. Scott Bruce of the Virginia Department of Environmental Quality was on a well drilling team that in 1983 began examining the Newport News area of Virginia. The team expected to see neat layers of sand, clay, and the associated fossils in the core samples it collected at various depths. Instead, the samples showed layers that were jumbled and mixed. Figuring that these samples became mixed during collection, the core drilling team moved eastward looking for more favorable sites.

At about the same time, evidence of a bolide impact off the East Coast of the U.S. came to light. C.Wylie Poag was chief scientist on a drill ship, the Glomar Challenger. Ninety miles east of Atlantic City, New Jersey, Poag was working at a core site known as DSDP 612 . During routine examination of core samples, he began to recognize evidence of a meteorite. Analysis of the cores revealed the telltale evidence. Within the cores samples were shocked quartz, which are battered crystals that show multidirectional patterns of parallel fractures and are hallmarks of impacts from space. In addition, Poag's team detected microtektites, which are droplets of molten rock vapor blasted into theatmosphere after a massive impact. There were also microfossils from the late Eocene Epoch found in the debris of the impact indicating that the meteorite collided with the Earth 35 million years ago!

Poag reasoned that the core samples of microtektities were associated with the North American Tektite Strewn Field and that the source of these tektites was presumably a meteorite impact now buried to the west of the drilling site.

He furthered reasoned that the tektites were from an impact, but where? Not on the East Coast at the surface or on the Atlantic sea floor since these areas had been surveyed. The crater must be buried, hidden, and covered with sediments. But where? Poag began to use the USGScollection of offshore seismic reflection profiles to search for buried craters. Poag first hypothesized that the USGS seismic studies pointed to a small impact structure off the coast of New Jersey, now known as the Tom's Canyon crater. The crater is near DSDP 612, which was where he was examining the core samples at the time. Intrigued by the evidence, he learned about the work of David Powars of the U.S. Geological Survey and Bruce of the Virginia Department of Environmental Quality.

Powars was part of a research team drilling cores to study the subsurface layers across Virginia's Coastal Plain. The team was gathering hard data and was systematically drilling cores from Fredericksburg to the Atlantic Ocean. T. Scott Bruce's team needed a test hole drilled. Powars's team needed the core from such a hole. The groups joined forces in 1986 and,on a sultry August night, a very special core sample was brought to the surface. This was a core sample that none had every seen before.

Powars and Bruce noted the abnormalities, which were easy to spot, in the Exmore core sample. Instead of the expected clays and uniform layers of the Coastal sediments, the teams saw a twisted and confused mix of layers. It was the most exciting thing the teams had ever seen!

Powars thought that he had read of this jumbled layer before. In 1913, Samuel Sanford and John Cederstrom had recorded in careful detail the first report of Virginia's groundwater in the Coastal Plain. Drawing contour lines connecting known wells that contained equal concentrations of salt, he noted an "inland bulge" around thelower Chesapeake Bay, centered around the tiny town of Cape Charles on Virginia's Eastern shore.

The methods of core analysis were much cruder at the time. Coredrilling was expensive. Cederstrom had to content himself withliterally cataloging chips and pieces that were flushed up and out of wells that were being dug. He noted that the orderly layers of the Coastal Plain at one point became mangled and mixed. He called this strange batch of sediments the Mattoponi formation from a local Indian name. He also noted something else unusual, a low spot, perhaps afault, where southeastern Virginia subsurface layers seemed to dropaway.

What Cederstrom didn't find was freshwater. Aquifers flowing downfrom the west contained salt. Drilling 52 wells and connecting the salinity contents, Cederstrom noted what Powars would later recognize -- the "inland saltwater wedge."

Fellow scientists at that time did not accept Cederstrom's conclusion that the Mattoponi formation was somehow involved with the salinity in theaquifers, and Cederstrom's work was scorned as being inaccurate.

Saltwater aquifers had been known in the area since the Civil War. Union soldiers stationed at Fort Monroe were plagued by cisterns that dried upduring long hot summers. In 1864, the fort began to drill a well. Forfive years, the drillers labored. Finally, they reached water, but it wastoo salty to drink. They drilled deeper still, until they reached 907 feet. But the water was still too salty to drink, and they eventually gave up.

No one knew why the water was salty or why the James River took a sharp 90-degree turn to the northeast near Fort Monroe. Neither thewell nor the course of the river was following the usual patterns.

The normal course of rivers flowing from the mountains to the sea along the East Coast is predictable. They gently incline toward the Atlantic. However, the James, Rappahannock, and York rivers flow in this fashion until they near the coast. There, they bend abruptly and turn their open mouths north and east to face the tiny village of Cape Charles.

Poag, noting the findings of Powars and Bruce, analyzed some samples of what is now known as the Exmore breccia. Poag found age-scrambled rock fragments and shocked quartz in the breccia. Early on, he thought that the breccia was produced by a tsunami from the smaller impact he referred to as the Tom's Canyon Crater. However, additional data from the release of Texaco's seismic analysis of the Exmore area revealed exhilarating information. The Texaco seismic analysis revealed to Poag a huge crater buried beneath the Chesapeake Bay. Poag then collaborated with the National Geographic Society and the Lamont-Doherty Earth Observatory of Columbia University for new seismic surveys of the area. Through the use of gravity surveys, a much more detailed structure and the shape of a crater were revealed.

The hypothesis that a large meteorite impacted the Atlantic Ocean during the Eocene Epoch was tested and, through dogged research, scientists came to the inescapable conclusion that Virginia had been impacted and affected by an Earth-changing event.
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In 2029, an asteroid will come within 20,000 miles of Earth. The chance of hitting Earth are 1/45,000.

It's bigger than of FedEx Field. It'll be a blast.

Bofunk Wrote:
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> In 2029, an asteroid will come within 20,000 miles
> of Earth. The chance of hitting Earth are
> 1/45,000.

Assuming it continues on the current path, which space stuff rarely does. It was supposed to hit Earth when it was discovered.

_____________
We are all Eesh.

Destination: The Lamb Center

Fascinating.

There are also two extinct volcanoes in Virginia... Believe it or not! More information from this link...

http://articles.washingtonpost.com/2012-12-15/local/35846544_1_volcanoes-molten-rock-mole-hill

Jack Palance Wrote:
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> There are also two extinct volcanoes in
> Virginia... Believe it or not! More information
> from this link...
>
> http://articles.washingtonpost.com/2012-12-15/loca
> l/35846544_1_volcanoes-molten-rock-mole-hill

Thanks for the link, I didn't know about these two.

There are actually more than two volcanoes...

Virginia’s volcanic past: Mole Hill and Trimble Knob
http://articles.washingtonpost.com/2012-12-15/local/35846544_1_volcanoes-molten-rock-mole-hill

Rest assured that Virginia’s two best-known volcanoes — Mole Hill in Rockingham County and Trimble Knob in Highland County — are in no danger of blowing their tops. Elizabeth Johnson, assistant professor in the department of geology and environmental science at James Madison University in Harrisonburg, said their erupting days are long over.

Well, long over in human terms. On the geologic scale, their period of activity — which was roughly a 2-million-year span 47 to 49 million years ago, during the Eocene epoch — was fairly recent.

“These are particularly interesting volcanoes, not because we’ re worried they’re going to erupt tomorrow,” she said. “They are very young geologically. They’re the youngest volcanoes anyone knows about on the East Coast of the United States.”

And what may be most interesting is this: Geologists aren’t sure why they erupted in the first place.

Volcanoes typically form where tectonic plates — those big, sliding pieces of the Earth’s crust — come together and rub against one another. But 50 million years ago, the nearest plate boundary was where it is today: out in the Atlantic Ocean.

“It’s a bit of a mystery why these things would erupt during that time,” Johnson said. “We’re interested in trying to figure out why that happened.”

Scientists may not know the why, but they’re pretty sure about the how: 49 million years ago, molten rock known as magma bubbled below the Shenandoah Valley at a depth of 40 to 65 kilometers, roughly 20 to 30 miles. Conduits in the mantle, the layer under the Earth’s crust, allowed the magma to rise. The magma exploded upwards at the surface through cracks in the crust. Mole Hill and Trimble Knob are actually remnants of the insides of the volcanoes, where the magma cooled. They were once surrounded by softer rock that has eroded substantially in the intervening millennia.

Geologists know they are volcanoes because, while most of the Shenandoah Valley is composed of sedimentary rock, Mole Hill and Trimble Knob are composed of igneous rock, mainly basalt. But as the magma rose, it picked up other rocks along the way, bringing those to the surface. These rocks — called xenoliths (“xeno” for foreign, “liths” for rocks) — can tell scientists what the composition is like miles down.

Not every gentle dome in Virginia is an old volcano. But Johnson said there are plenty more volcanoes in the commonwealth besides Trimble Knob and Mole Hill. She’s counted in excess of 100 on maps, giving her and her students plenty to work with. Every semester they visit different ones, taking rock samples that will be sliced and scrutinized.

Are the volcanoes related in any way to last year’s Virginia earthquake? Hard to say, but probably not. The fault along which that earthquake was centered is southeast of the volcanic outcrops, on the other side of the Blue Ridge. Johnson said there are other geologic processes at work, though further study is required to determine exactly what’s going on down there.

The two volcanoes are on private property. Gerald Knicely’s parents owned a dairy farm on the north side of Mole Hill — “what we always called the front side,” he told Answer Man. His bicycle store in Dayton, Va., is called Mole Hill Cycles. Two years ago, he bought 46 acres of Mole Hill and arranged to have them protected through a conservation easement with the Virginia Outdoors Federation.

“I spent many hours tromping through the woods as a child,” he said. “I wanted to see it stay Mole Hill.”

Answer Man asked Johnson why humans are so fascinated by volcanic activity. One reason, she said, is because of a volcano’s sheer power. “People can’t do anything about it,” she said. “It’s so hot and so uncontrollable. It’s something that’s happening that doesn’t have anything to do with other parts of human life at all, with everyday life like driving to the grocery store.”
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Commander Data Wrote:
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> And what may be most interesting is this:
> Geologists aren’t sure why they erupted in the
> first place.
>
> Volcanoes typically form where tectonic plates —
> those big, sliding pieces of the Earth’s crust
> — come together and rub against one another. But
> 50 million years ago, the nearest plate boundary
> was where it is today: out in the Atlantic Ocean.
>
> “It’s a bit of a mystery why these things
> would erupt during that time,” Johnson said.
> “We’re interested in trying to figure out why
> that happened.”
>
> Scientists may not know the why, but they’re
> pretty sure about the how: 49 million years ago,
> molten rock known as magma bubbled below the
> Shenandoah Valley at a depth of 40 to 65
> kilometers, roughly 20 to 30 miles. Conduits in
> the mantle, the layer under the Earth’s crust,
> allowed the magma to rise. The magma exploded
> upwards at the surface through cracks in the
> crust. Mole Hill and Trimble Knob are actually
> remnants of the insides of the volcanoes, where
> the magma cooled. They were once surrounded by
> softer rock that has eroded substantially in the
> intervening millennia.

So we have a state full of volcanoes that are extinct, yet we don't why they erupted only how they did and when they did. If the plates are out in the Atlantic ocean then how could one or more volcanoes have formed here?

Any accessible lava tubes at aforementioned Mole Hill and Trimble Knob worth the trek from FFX to explore?

Speelunka Wrote:
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> Any accessible lava tubes at aforementioned Mole
> Hill and Trimble Knob worth the trek from FFX to
> explore?

Unknown, there are literally hundreds of volcanoes in the state. I would imagine at least some should have lava tubes that are intact.

Is that 1,500 in Ken Cuccinelli years?

Speelunka Wrote:
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> Any accessible lava tubes at aforementioned Mole
> Hill and Trimble Knob worth the trek from FFX to
> explore?

Not that I was able to find.

Did you know that an asteroid hit VA 35 million years ago? new
Posted by: Mr. Spock ()
Date: July 06, 2013 07:49PM

Yes, This is an well known fact today. When this happened most of Virginia up to the mountain area was under water for awhile. That's why sea shell fossil can sometimes be dug up by fossil hunters in Virginia and West Virginia.

The key challange now is "Astroid Mining" as being discussed by National Space Society and others.


Cafe Twin
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Good info OP!!!!

>Fairfax County was a tropical rainforest.

This simply isn't possible. This would imply that the earth is cooling.

I suppose I will also mention: http://en.wikipedia.org/wiki/Continental_shelf

1 not in the Bible so its not true.
2. no one was there to witness it so not true
3. Possible it was something else so not true
4. All scientists are Atheists so not true.
5. Liberals are likely to believe this over bronze age tales so not true.

not in the Bible so its not true Wrote:
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> 1. not in the Bible so its not true.
> 2. no one was there to witness it so not true
> 3. Possible it was something else so not true
> 4. All scientists are Atheists so not true.
> 5. Liberals are likely to believe this over bronze
> age tales so not true.

These liberals and atheists are all so confused. Say Hallelujah! Then please send a generous check to support the work of The First Church of the Gooey Death and Discount House of Worship in Del Rio, Texas. Say Hallelujah!
.
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Let me tell you, I was there. It was a big thing. I said, "Don't look Cavewoman Ethel!" But it was too late. She was stoned.

And defense contractors still roam the Earth to this day.

Young Curmudgeon Wrote:
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> Bofunk Wrote:
> --------------------------------------------------
> -----
> > In 2029, an asteroid will come within 20,000
> miles
> > of Earth. The chance of hitting Earth are
> > 1/45,000.
>
> Assuming it continues on the current path, which
> space stuff rarely does. It was supposed to hit
> Earth when it was discovered.

Exactly. It may not hit, maybe. But do you think for a second that our leaders would tell us if it were going to hit? People can't handle minor hurricanes or even 2 inches of snow without panic. People would go crazy if the government said it was going to hit.