The lagoon of Caronte is during the Early Middle Ages a place of much passage and fishing, notably with bourdigues, big fish-traps, for which the lords of the area share the profits. The control of Caronte is also of military significance : it is an open door to the western Lower Provence. The founding of St-Geniès and the port of Bouc in the 12th c., of L'Ile-St-Geniès, of Ferrières and of Jonquières in the 13th c. makes up this boggy zone ; the urban landscape of Martigues takes shape circa 1400. In 1581, the town's birth comes about with the union of L'Ile, Ferrières and Jonquières. This is the basis of an economic and demographic boom. The town grows in an atypical way, demographic pressure inducing the creation by embankment of constructible sectors on the lagoon. In the 18th c., the shallow channels and the rivalry of the port of Marseille makes it difficult for Martigues to compete for shipping tonnage : up until the petrochimical era, the town has known a long atony.
