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 Ancient seawater was TWICE as salty as it is today, scientists learn

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تاريخ التسجيل : 07/10/2009
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مُساهمةموضوع: Ancient seawater was TWICE as salty as it is today, scientists learn   الجمعة 22 نوفمبر 2013, 2:00 am

Ancient seawater was TWICE as salty as it is today, scientists learn
Deep underground in Chesapeake Bay, Virginia, a large body of ancient seawater has been discovered. The find gives clues as to what the world's oceans were like during the time of the dinosaurs. Believed to be 100 to 150 million years old, samples suggest that the Atlantic was once twice as salty as it is now.
 

Likening the discovery to being "like a fly trapped in amber," the seawater was trapped by the aid of a massive comet or meteorite impact that struck the area about 35 million years ago, which created Chesapeake Bay.
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LOS ANGELES, CA (Catholic Online): The ancient sea water also contains chloride and bromide, which helped scientists age it to the Early Cretaceous Period.

"Previous evidence for temperature and salinity levels of geologic-era oceans around the globe have been estimated indirectly from various types of evidence in deep sediment cores," Ward Sanford, a United States Geological Survey research hydrologist says.


"In contrast, our study identifies ancient seawater that remains in place in its geologic setting, enabling us to provide a direct estimate of its age and salinity."

Likening the discovery to being "like a fly trapped in amber," the seawater was trapped by the aid of a massive comet or meteorite impact that struck the area about 35 million years ago, which created Chesapeake Bay.

The largest crater discovered in the U.S., the Chesapeake Bay impact crater is one of only a few oceanic impact craters that have been documented worldwide.

The impact from the comet ejected enormous amounts of debris into the atmosphere and spawned a train of gigantic tsunamis that probably reached as far as the Blue Ridge Mountains, more than 110 miles away.

Virginia's "inland saltwater wedge" is a well-known phenomenon that is thought to be related to the impact crater. The outer rim of the crater appears to coincide with the boundary separating salty and fresh groundwater.

"We knew from previous observations that there is deep groundwater in quite a few areas in the Atlantic Coastal Plain around the Chesapeake Bay that have salinities higher than seawater," Jerad Bales, acting USGS Associate Director for Water says.

"Various theories related to the crater impact have been developed to explain the origin of this high salinity. But, up to this point, no one thought that this was North Atlantic Ocean water that had essentially been in place for about 100 million years.

"This study gives us confidence that we are working directly with seawater that dates far back in Earth's history," Bales added.
 
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Ancient seawater was TWICE as salty as it is today, scientists learn
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