A study looked at how sand has been accumulating on the Virginia coast over the past 2000 years. They focused on three barrier islands and found that they trapped a huge amount of sand, which affected the shape of the islands. About 190 years ago, the islands stopped growing due to less sand coming in, but then started growing again. The researchers think that the way the islands trap sand and the direction of the waves are important factors in how the islands change shape over time.