Scientists discovered staggeringly ancient water at the bottom of the Chesapeake Bay.
The high-salinity water found 1,000 miles beneath the bay's surface is believed to be leftovers from the Early Cretaceous North Atlantic Sea, a U.S. Geological Survey news release reported.
The water is most likely between 100 and 145 million years old and is twice as salty as modern-day seawater.
"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," said Ward Sanford, a USGS research hydrologist and lead author of the investigation. "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."
The Chesapeake Bay is located in the largest crater that has ever been discovered in the U.S., it is believed to have been formed when a giant meteorite or comet smashed into the Earth millions of years ago. The impact would have preserved the water "like a fly in amber" the news release reported.
The space rock (or ice) created a 56-mile-wide crater in the ocean floor 35 million years ago, this is now the bay. The event may have triggered tsunamis that reached as far as 110 miles away.
The impact would have broken down water-bearing and groundwater-controlling rocks, and may have created the nearby "inland saltwater wedge." The edge of the crater is believed to separate the fresh and salty water.
"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, said. "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," he said. "The study also has heightened our understanding of the geologic context of the Chesapeake Bay region as it relates to improving our understanding of hydrology in the region."
