Scientists drilling in the Chesapeake Bay say they’ve found the oldest body of seawater ever found.
The water is estimated to be 100 to 145 million years old and was found 1.1 miles deep inside a massive crater.
According to National Geographic, that crater was formed about 35 million years ago when a large rock or chunk of ice slammed into the eastern shore of North America and led to the formation of what is now the Chesapeake Bay.
“The water was in the sediment long before the impact occurred. The impact simply reshuffled the sediment in large blocks, which helped preserve it,” study leader Ward Sanford, a hydrologist with the U.S. Geological Survey, told National Geographic.
The water was collected in 2005 when Sanford and his colleagues drilled into the crater during a joint project with the International Continental Scientific Drilling Program.
Through a variety of chemical processes, the team found the origin of the water and rough age over the course of eight years.
The discovery is helping scientists clear up the mystery of why previously collected samples of deep groundwater from the Chesapeake Bay are so salty.