Pays de France  The Pays de France, also called the Parisis or Plaine de France, is a natural region located in the Île-de-France administrative region to the north of Paris, France. It is essentially a silt plain devoted to cereal crops, of which the southern part is included in the northern suburbs of Paris and greatly urbanised, and also includes Charles de Gaulle Airport. Administratively, the region corresponds approximately to the east of Val-d'Oise department, with part of Seine-Saint-Denis and the northwestern fringe of Seine-et-Marne. The Pays de France is delimited in the south west by the Seine, in the west by the forests of Montmorency and Carnelle, in the east by the River Marne and the heights of Dammartin and Goële, and in the north by the Chantilly Forest and . It is bordered by the Vexin français to the west, by Brie to the east, by Multien and Goële to the north east, and by Valois and the Pays de Thelle to the north. To the south are Mantois, Hurepoix and the Pays d'Aulnoye. In modern times, the Parisian agglomeration has encroached on many of these traditionally defined areas and now makes up a new form of natural region. Two tectonic accidents have had a powerful influence on the geological structure of the Pays de France: the Seine syncline with the associated Saint-Denis basin, in the west, and the Louvres anticline, in the east. The outcrops, such as the Butte-Pinson at Montmagny, Pierrefitte and Villetaneuse and the Butte d'Écouen at Villiers-le-Bel and Écouen, contain significant deposits of gypsum; which was mined both in open pits and underground until the first half of the twentieth century. The mining has weakened the structure of the ground to the extent that several risk prevention plans need to be developed. One very large depression, across, between Dugny and the Seine, is traversed by three small rivers: the Croult, the Vieille Mer and the Rouillon. The upper water table (Eocene strata) includes two lower-level aquifers up to in total height. It forms part of the general water table which is fed both by the watershed of the Seine and Marne and by lower aquifers.