Puddingstone, or Conglomerate, a consolidated shingle, consisting of rounded fragments or pebbles, generally siliceous, cemented together either by carbonate of lime, silica, iron-oxide, or other material. The formation of such a bed may indicate a considerable lapse of time, since a rock must be consolidated and exposed to denudation before pebbles can beformed from it, and then the pebbles require to be cemented. The name puddingstone is specially applied to a conglomerate in the Woolwich Beds (q.v.) of Hertfordshire, consisting of black (raisin-like) flint pebbles in a brown ochreous (pudding-like) cement. The unequal hardness of the two materials caused this rock to be used for handmills or querns.