The Boulonnais brings together diverse terrains: the marble of Marquise, the sandstone of Outreau, the chalk of Desvres and Neufchâtel. Between Guînes and the Aa River, the bare plateau, occasionally scattered with clusters of trees, opens out into immense unobstructed vistas. There are large farms growing cereals and beetroots. The Wimereux, Liane, Hem and Slack Valleys are covered with cider apple trees and prairies where local breeds of cow (Bleue du Nord and Rouge flamande) graze alongside sheep and "Boulonnais" horses.