Durgerdam, Polder IJdoorn, after the St. Elizabeth flood of 1421, in the 1422s the Waterlandse Zeedijk was shifted to the current inlaagdijk, while the IJdoornpolder was placed outside the dyke , only protected by a summer dyke..© 11 juni 2018 Marco van Middelkoop/Aerophoto-Schiphol