Scientists say that they have discovered seawater, which is believed to be over 100 million years old, in a giant crater in the Chesapeake Bay.

Ward Sanford, a hydrologist at the United States Geological Survey (USGS), who heads the team of researchers suggest that the seawater could be anything between 100 to 150 million years old. Sanford said that the seawater is deposited between layers of sediment deep under present day Cape Charles.

The researchers indicate that a large asteroid or a comet impact on Earth around 35 million years ago may have helped to isolate the seawater and prevented it from being flushed out.

"What we essentially discovered was trapped water that's twice the salinity of [modern] seawater," said Sanford. "In our attempt to find out the origin, we found it was Early Cretaceous seawater. It's really water that's from the North Atlantic."

In 2004, Sanford and his team started drilling at Cape Charles and drilling just a half-mile from the surface, the team discovered standing water. Initially, researchers thought they have come across regular sea water that occasionally shows up while drilling at coastal sites. Sanford said that saltwater is found underground because of huge salt deposits in the ground.

However, the team of researchers did not find any salt deposits while drilling. Scientists then thought that the saline water is due to the boiling theory, which is when a meteor impacts the Earth with high force it heats the water and then increases the salinity of the water. However, tests of the water rejected the boiling theory as well.

Further tests revealed that the sea water was two times saltier than the sea water of present day. Moreover, the tests also revealed that the water had high levels of chlorides and bromides, which indicates that the sea water is not from the current time.

Detailed study of the water also found that the sea water had high halite deposits, which was created during the Jurassic and Cretaceous periods in the Gulf of Mexico and South Atlantic Basins.