Time capsules aren’t limited to building cornerstones and the pedestals of statues. Geologists, for example, found one about two-thirds of a mile beneath Chesapeake Bay. Its treasure is the water of the ancient North Atlantic — water that’s been cut off from the ocean for more than a hundred million years.
Chesapeake Bay was gouged out by a mountain-sized space rock that slammed into Earth tens of millions of years ago. The impact squished layers of rock far below the surface. Some of those layers contained sea water that had seeped into the ground. The impact cut off a lake-sized pool of water, isolating it from other water sources and preserving a record of the distant past. In fact, it’s the oldest pool of ancient sea water yet discovered.
A team of geologists found the water several years ago. The scientists were studying the effects of the impact that created Chesapeake Bay. They were drilling deep into the rocks near Cape Charles, Virginia, near the bay’s mouth, when they hit the water.
Early measurements showed that it’s twice as salty as modern-day sea water. At first, the geologists supposed the water had accumulated the salt from the rocks that encased it. But detailed tests of its chemistry showed otherwise. Among other things, the ratios of certain elements in the water match those of salt formations known to be at least a hundred million years old.
The scientists describe the find as “like sea water trapped in amber” — a relic of the distant past preserved in a rocky time capsule.
