I think it's so cool that: 1) The Chesapeake Bay was formed by an impact from a giant asteroid or comet, 2) the north Atlantic used to be a small sea that evaporated so much it was left extra salty, and 3) scientists can drill and encounter ancient seawater deep below the current ocean floor and test the water samples to see how they are chemically different from today.
http://www.livescience.com/41182-ancient-salty-oceans.html
http://www.livescience.com/41182-ancient-salty-oceans.html