A Swamp in the Landes, after 1844. Rousseau worked on the Normandy coast early in his career but also studied the sea on a visit to the Landes region in southwestern France in 1844. Here, he depicts a luminous view looking out across expansive marshes with sails visible on the horizon. Technical analysis of a cross section of this painting has demonstrated that Rousseau was using the recently discovered pigment emerald green.