EMBANKMENT  , in

engineering, a mound of earth or stone, usually narrow in comparison with its length, artificially raised above the prevailing level of the ground . Embankments serve for two main classes of purpose . On the one hand, they are used to preserve the level of railways, canals and roads, in cases where a valley or piece of low-lying ground has to be crossed . On the other, they are employed to stop or limit the flow of water, either constituting the retaining wells of reservoirs constructed in connexion with water-supply schemes, or protecting low-lying tracts of land from river floods or the encroachments of the sea . The word embankment has thus come to be used for the mass of material, faced and supported by a stone wall and protected by a parapet, placed along the banks of a river where it passes through a city, whether to guard against floods or to gain additional space . Such is the Thames Embankment in London, which carries a broad roadway, while under it runs the Under-ground railway . In this sense an embankment is distinguished from a quay, though the mechanical construction may be the same, the latter word being confined to places where ships are loaded and unloaded, thus differing from the French quai, which is used both of embankments and quays, e.g. the Quells along the Seine at Paris .