The Mystery of the Shifting Shorelines

The clues: A photo of a historic building on the shore, a hard hat, and a map of bird migration The file label: "To fill or not to fill" The gang is perplexed to learn that a building that used to be on the shore is now inland. How could that happen? Kyla goes to check out the building's archives. Meanwhile, E.B. follows the hardhat clue to a construction site, where he learns about landfills, and then goes to the Leslie Street Spit -- a landfill that is now a nature reserve. With Tilly's help, the kids discover that many waterfront cities create extra land by using landfill.