SOMME, a department of France, formed in 1790 of a large part of the province of Picardy (comprising Vermandois, Santerre, Amienois, Ponthieu, Vimeu and Marquenterre) and a small portion of Artois. Pop. (1931), 466,626. Area, 2,443 sq. miles. It is bounded on the north by Pas-de-Calais, east by Aisne, south by Oise, and south-west by Seine-Inferieure, and its sea-coast extends 28 m. along the English channel. Two streams flowing into the channel—the Authie on the north and the Bresle on the south west—bound it in these directions. The department is part of the chalk plateau of north-west France, cut by the English channel on the west, with the result that it is seamed by well-marked valleys, showing a succession of terraces which have become classical ground for the student of geology and of palaeolithic man. On the plateau, which rises to about 700 ft. where it approaches the Pays de Bray in the south-west, there are large stretches of limon, a fine grained, porous, fertile material. The Somme is a historic zone of defence of Paris, and the whole district east of Amiens bears the traces of ceaseless fighting during the war of 1914-18. The river Somme has been made navigable by canalization of stretches. It also supplies considerable power. From Abbeville to the sea its canalized course can take ships of considerable size. From the mouth of the Authie to the Bay of the Somme the coast is lined with sand dunes about 2 m. broad, behind which is the Marquen terre, a tract of 50,000 ac. reclaimed from the sea by dykes, and traversed by drainage canals. The Bay of the Somme, obstructed by dangerous sandbanks, contains the fishing ports of Le Crotoy, St. Valery, which is also the chief commercial port, and Le Hour
del. Next come the shingle banks, behind which the low fields of Cayeux (2 5,00o ac.) have been reclaimed; and then at the hamlet of Ault begin the chalk cliffs, which continue onwards into Nor mandy. Near Amiens the Somme is joined by the Ancre from the north-east, the Avre from the south-east and the Selle from the south. The Bresle is a small river south of the Somme, reaching the sea at Treport.
The department, especially in the north-east, is one of the best cultivated in France. Beetroot for sugar is the staple crop of the Peronne arrondissement ; cereals, chiefly wheat and barley, sugar beet, fodder and mangel-wurzels, oil plants, colza, flax, hemp and potatoes are grown throughout the department. Stock-raising of all kinds is successful.
The chief towns are Amiens (the capital), Abbeville, Mont didier, Peronne, Doullens, St. Riquier, Crecy and Ham (qq.v.). Albert (pop. 8,128) is a centre for machine construction; Villers Bretonneux (pop. 3,631), a centre of hosiery manufacture; Corbie was once celebrated for its Benedictine abbey (founded in the 7th century) the church of which (16th-18th century) is still to be seen, though now ruined. Folleville has a church (15th century) containing the Renaissance tomb of Raoul de Lannoy; Picquigny has the remains of a château of the 14th, 15th and i6th centuries, once one of the chief strongholds of Picardy; Rue has a 15th century chapel; and Tilloloy a Renaissance church.