An elevated mound of earth, part of the motte-and-bailey castle, which was crowned with a timber palisade and surrounded by a defensive ditch that also separated the motte from a palisaded outer compound, called the bailey. Access to the motte was by means of an elevated bridge across the ditch from the bailey. This structure appeared in the 10th and 11th centuries between the Rhine and Loire rivers and eventually spread to most of western Europe. The motte was usually made of earth, but sometimes of stone. Attached to it may be one or more baileys, which are enclosures surrounded by ramparts or stone walls. Motte should not be confused with moat; the latter was a ditch. The motte was formed from the soil originally dug from the ditch. It was the mound on which the wooden castle of the motte and bailey was built in early Norman times. Motte-and-bailey was the type of wooden castle first erected by Norman conquerors and it was an expedient, quickly erected, medieval fortification. Several classic examples of motte and bailey castles are illustrated in the Bayeaux tapestry, with wooden towers and palisades on top of the motte.